Trisiloxane, octamethyl- (MDM)

Trisiloxane, octamethyl-
CAS Registry Number 107-51-7

What is it?

  • Trisiloxane, octamethyl-, also known as MDM, is an industrial chemical. It is not expected to occur naturally in the environment.

How is it used?

  • MDM is primarily used as an ingredient in the preparation of polymethylsiloxane (PDMS) polymers, which are in turn added as ingredients to a number of industrial and consumer products. PDMS formulations containing MDM may be found in cleaning and degreasing products, lubricants, diluents and solvents, cosmetics including personal care products.
  • This substance is not manufactured in Canada but is imported into Canada.

Why is the Government of Canada assessing it?

  • Prior to assessment, MDM was identified as a potential concern to the environment based on information regarding possible persistence, accumulation in organisms and potential to cause harm to organisms.
  • MDM was not considered to be a high priority for assessment of potential risks to human health; however, potential health effects were also evaluated in this screening assessment.

How are Canadians exposed to it?

  • Canadians may be exposed to MDM through indoor air.
  • Canadians may also be exposed to MDM during the use of cosmetics and personal care products containing this substance.

How is it released to the environment?

  • Releases of MDM to the environment may occur during processing, transportation and storage of the substance, as well as during service life and disposal of products containing MDM.
  • Most releases of MDM are expected to be to air.

What are the results of the assessment?

  • The Government of Canada has conducted a science-based evaluation of MDM, called a screening assessment.
  • Screening assessments address the potential for harm to the general population of Canada and the environment.
  • Results of the final screening assessment indicate that MDM has the potential to remain in the environment for a long time and accumulate in organisms.
  • However, the quantity of MDM that may be released to the environment is below the level expected to cause harm to organisms.
  • The Government of Canada has therefore concluded that MDM is not entering the environment at levels that constitute a danger to the environment.
  • The Government of Canada has also concluded that MDM is not harmful to human health at current levels of exposure.
  • Hazards related to chemicals used in the workplace should be classified accordingly under the Workplace Hazardous Materials Information System (WHMIS).

What is the Government of Canada doing?

  • The Final Screening Assessment for MDM was published on March 28, 2015.
  • Based on the conclusion of the final screening assessment, the Government of Canada proposes that no further action be taken on MDM.

What can Canadians do?

  • The health risks associated with a chemical depend on the hazard (its potential to cause health effects) and the dose (the amount of chemical to which you are exposed). MDM is not a concern for the environment or health of the general population in Canada at current levels of exposure.
  • As a general precaution, Canadians are reminded when using any product to carefully follow any safety warnings and directions.
  • Canadians who may be exposed to MDM in the workplace should consult with their employer and occupational health and safety representative about safe handling practices, applicable laws and requirements under the Workplace Hazardous Materials Information System (WHMIS).
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