November 15, 2004

Ontario revises metal criteria for compost to match CCME guidelines

New composting standards announced last week by the Ontario government will harmonize the provincial standards with those of the rest of Canada. This, said Environment Minister Leona Dombrowsky, will make it easier for communities to set up composting programs. "Organic waste is a resource, not garbage," she stated, adding that "the alignment of Ontario's composting standards with those of the other provinces will remove a major barrier to municipal composting programs while ensuring that the environment and public health are protected."

The Ministry of Environment has updated its "Interim Guidelines for the Production and Use of Aerobic Compost in Ontario" by adopting the Category A criteria for 11 heavy metals set by the Canadian Council of Ministers of Environment (CCME). The MOE's guidelines, issued in 1991, set criteria for metals based on an objective of not significantly affecting background soil levels when using compost in an unrestricted manner.

Many communities in Ontario found the existing standards hard to meet, with the result that organics which could be composted were instead often sent to landfills. The CCME criteria for metals are contained in its 1996 "Guidelines for Compost Quality." These guidelines are based on several objectives, including protection of the environment and public health and encouragement of source separation of municipal solid waste (MSW) to produce high-quality compost. Other provinces have previously adopted the CCME guidelines.

"Updating the guidelines to the Canadian standard opens up greater opportunities for composting in Ontario," says Susan Antler, executive director of the Composting Council of Canada. "There will be a greater number of markets available now for the compost produced which will provide even further momentum for composting's expansion in the province."

Under the new guidelines, criteria for cadmium, lead, selenium and zinc remain unchanged, at 3.0 mg/kg, 150 mg/kg, 2.0 mg/kg and 500 mg/kg, respectively. New criteria for the remaining seven metals are: arsenic, 13 mg/kg (up from 10 mg/kg); chromium, 210 mg/kg (up from 50 mg/kg); cobalt, 34 mg/kg (up from 25 mg/kg); copper, 100 mg/kg (up from 60 mg/kg); mercury, 0.8 mg/kg (up from 0.15 mg/kg); molybdenum, 5.0 mg/kg (up from 2.0 mg/kg); and nickel, 62 mg/kg (up from 60 mg/kg).

The Ministry's decision can be viewed on-line at

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