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Siloxane D4 in Industrial Effluents

Response to Comments

Summary of Comments and Environment Canada’s Response to Comments Following Consultations on the Proposed Risk Management Instrument to Control the Release of Cyclotetrasiloxane, octamethyl- (Siloxane D4) , (CAS No.1 556-67-2)


Chemical Production Division
Environment Canada



The final Screening Assessment Report 2 published in November 2008, concluded that Cyclotetrasiloxane, octamethyl- (D4) meet the criteria under paragraph 64 (a) of the Canadian Environmental Protection Act, 1999 (CEPA 1999). The final Screening Assessment Report also concluded that D4 meets the criteria for persistence as set out in the Persistence and Bioaccumulation Regulations, but it is not possible to conclude at this time that D4 meets the criterion for bioaccumulation as set out in the Persistence and Bioaccumulation Regulations

The Proposed Risk Management Approach 3, published in January 2009, recommended, as one of the risk management actions to protect the environment, that a regulation be developed to reduce release of D4 from industrial facilities.

A consultation meeting was held in Toronto (Ontario) on August 10-11th 2010.  The objective of the meeting was to give interested and affected parties an opportunity to provide input into the development of a D4 regulatory proposal.  This was followed by a comment period that ended on September 3rd 2010.  During the comment period, 11 individual submissions were received. Comments received during the consultation session and the consultation periods were considered during the development of this proposed risk management instrument.

Following the consultation and based on further analysis of available information, Environment Canada is proposing to use the pollution prevention planning provisions of CEPA 1999 as the risk management instrument to address the release of D4 from industrial facilities instead of regulations.  A Pollution Prevention (P2) Planning Notice has been determined to be the preferable instrument, considering the limited existing data on concentrations of D4 in industrial effluents.  The use of a pollution prevention planning notice will also help Environment Canada to gather more information on industrial releases of D4.  Environment Canada will continue to monitor Canadian surface waters, wastewater treatment plant influents and effluents and industrial effluents to inform future decisions on D4.

A summary of the comments received on the proposed instrument, and Environment Canada’s responses can be found below, organized by the following topics

  • General Comments on the Instrument
  • Application and Exemptions
  • Release Limits
  • Sampling and Analysis
  • Reporting
  • Accidental Release
  • Guidance Document
  • Environmental Monitoring
  • Technology / alternatives
  • Economics

It should be noted that elements of the best management practices that were mentioned in the consultation document under the Substance Management Plan section have been integrated into the “Factors to consider” of the proposed P2 Planning Notice.

It should also be noted that this document focuses on comments made on the proposed risk management instrument.



1 The Chemical Abstracts Service (CAS) Information is the property of the American Chemical Society and any use or redistribution, except as required in supporting regulatory requirements and/or for reports to the Government when the information and the reports are required by law or administrative policy, is not permitted without the prior, written permission of the American Chemical Society.

2 Screening Assessment Report

3 Proposed Risk Management Approach

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