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Ontario: New Report Details Status of Tier 1 and Tier 2 chemicals in the Great Lakes basin under the Canada-Ontario Agreement

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The status of Tier 1 and Tier 2 chemicals in the Great Lakes Basin under the Canada-Ontario Agreement provides information on the current trends of the chemical in the Great Lakes Basin over time, related to its use, release and environmental concentrations in ambient air, surface water, sediment, fish and Herring Gull eggs. A summary of current and past risk management actions, research, monitoring and surveillance activities for these chemicals that the Ontario provincial government and the Canadian federal government have undertaken is also provided.

Status of Tier 1 chemical concentrations in the environment
Concentration levels of most Tier 1 chemicals have gone down over time across the Great Lakes, in water, sediment, fish and Herring Gull eggs.
  •  Only two chemicals have concentrations above water quality guideline levels (HCB and PCB).
  • Four chemicals have concentrations in sediments that are above guideline levels: benzo(a)pyrene, chlordane (near urban areas), mercury and PCBs. Based on the environmental persistence of these chemicals, concentrations may continue to be elevated in the future.
  • Fish consumption advisories still exist for select compounds in different Great Lake regions (chlordane, dioxins/furans, mercury, mirex, PCBs, and toxaphene). This is due to the persistence of these chemicals in the environment and their ability to build up in fish tissues (Table 1).
Action and status of Tier 2 chemicals
Similar to the Tier 1 chemicals, Canada has regulated the use of many Tier 2 chemicals. For instance:
  •  Canada banned the use of tributyltin as an anti-fouling paint for ships in 2003.
  • The use of pentachlorophenol is restricted to heavy-duty wood preservation applications.
  • The only non-restricted use of lindane in Canada is as a second-line treatment for head lice or scabies, and there is limited use of 4,4’-methylenebis (2-chloroaniline) (or MBOCA) in Ontario.
  • Dinitropyrene is not produced for a specific purpose or use in Canada; it is a product of diesel and gasoline consumption.
Other Tier 2 chemicals continue to have commercial and industrial uses and/or releases:
  • Cadmium continues to be released into the Canadian environment from metals production (particularly base-metal smelting and refining); stationary fuel combustion (power generation and heating); transportation; and solid waste disposal and sewage biosolid applications.
  • 1,4-Dichlorobenzene is released to the environment from its widespread use as an industrial deodorant.
  • Certain PAHs continue to be released to the environment from incomplete combustion from different manufacturing processes.
The report details actions taken on individual chemicals, gives concentration levels and more.


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