Siloxane D5 (cyclopentasiloxane, decamethyl-) - information sheet

(D5; cyclopentasiloxane, decamethyl-)
CAS Registry Number 541-02-6

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  • The Government of Canada conducts risk assessments of substances under the Canadian Environmental Protection Act, 1999 (CEPA) to determine whether they present or may present a risk to human health or to the environment.
    • The risks posed by a substance are determined by both its hazardous properties (potential to cause adverse human health or ecological effects) and the amount or extent of exposure to people and the environment.
    • When needed, the Government implements risk management measures under CEPA and other federal acts to help prevent or reduce potential harm.
  • Siloxane D5 is associated with health and ecological effects. At levels of exposure considered in the assessment (2009) and as a result of the revised decision (2012) for siloxane D5, the Government concluded that siloxane D5 is not harmful to human health or to the environment.

About this substance

  • The screening assessment focused on the substance decamethylcyclopentasiloxane, also referred to as D5. This substance was assessed as part of Batch 2 of the Challenge initiative of the Chemicals Management Plan (CMP).
  • D5 does not occur naturally in the environment. According to information gathered by the Government, D5 was imported into Canada in very high quantities and was mainly used in products available to consumers, such as hair and skin products, and antiperspirants. It was also used as a commercial dry cleaning fluid, as well as in the manufacture of silicone polymers.
  • Silicone polymers that may contain residual amounts of D5 are used in biomedical applications, pharmaceuticals, in certain pest control products and in industrial processes as surfactants (detergents) and defoamers (anti-foaming agents). They are also used in lubricants, cleaning products, sealants, adhesives, waxes, polishes, and coatings.

Human and ecological exposures

  • The assessment indicated that Canadians may be exposed to D5 from environmental sources (for example, air, water and soil), food and from using certain products available to consumers, including cosmetics and other products available to consumers.
  • D5 is persistent (able to remain for a long time) in air and the aquatic environment.
  • The assessment indicated that D5 may be released to the environment as a result of industrial processes and during the use and disposal of cosmetics and other products available to consumers.

Key health and ecological effects (hazard)

  • Information available at the time of the assessment indicated that D5 may have carcinogenic effects (potential to cause cancer), as well as effects on the liver. These were considered to be the important or critical effects used for characterizing the risk to human health in the assessment.
  • The 2009 assessment found that given the elevated persistence and accumulation potential for D5, long-term environmental exposure to D5 may cause adverse effects to aquatic organisms. New hazard information on D5 considered in 2011, along with previously summarized studies, showed that D5 may not cause adverse effects to aquatic organisms; however, effects in some sediment organisms may still occur at higher concentrations.

Risk assessment outcomes

Revised screening assessment conclusions

  • The Government concluded that D5 is not harmful to human health at levels of exposure considered in the assessment.
  • As a result of findings and recommendations made by a Board or Review, and review of new information obtained since publication of the screening assessment in 2009, the Government concluded in 2012 that D5 is not entering the environment at levels that are harmful to the environment.

Related resources

  • D5 may be found in certain products available to consumers. Canadians should follow any safety warnings and directions on product labels and dispose of products responsibly.
  • Visit Healthy home for information on chemical safety in and around the home.
  • Federal Environmental Quality Guidelines (FEQGs) for D4 were published in June 2021 to be used as thresholds for comparison with environmental monitoring results. The aquatic biota tissue guideline for D4 can also be applied to the sum of cyclic volatile methyl-siloxanes (cVMS), which includes D5. Updates can be found on the FEQGs web page.
  • Use the Substances Search tool to find substances that are referenced in certain legislative or regulatory instruments or on Government of Canada websites.
  • The screening assessment focused on potential risks from exposure of the general population of Canada. Hazards related to chemicals used in the workplace are defined within the Workplace Hazardous Materials Information System (WHMIS). For information concerning workplace health and safety and what steps to take in the workplace, Canadians should consult their employer or the Occupational Health and Safety Regulator in their jurisdiction.

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