Siloxane D6 (cyclohexasiloxane, dodecamethyl-) - information sheet

Dodecamethylcyclohexasiloxane
(D6; cyclohexasiloxane, dodecamethyl-)
CAS Registry Number 540-97-6

Publications summarized:

Final Screening Assessment for Dodecamethylcyclohexasiloxane (D6) (published on January 31, 2009). Public comments received on the draft screening assessment were considered in development of the final screening assessment.
Associated notice: Canada Gazette, Part I: Vol. 143, No. 5 – January 31, 2009

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 D6 is associated with health effects; however, at levels of exposure considered in the assessment, the Government concluded that this substance is not harmful to human health or to the environment.

The screening assessment focused on the substance Dodecamethylcyclohexasiloxane, also referred to as D6 or cyclohexasiloxane, dodecamethyl-. This substance was assessed as part of Batch 2 of the Challenge initiative of the Chemicals Management Plan (CMP).
D6 does not occur naturally in the environment. According to information gathered by the Government, D6 was mainly used in blending and formulating of products available to consumers, such as hair and skin products, antiperspirants and in the manufacture of silicone polymers.
Silicone polymers that may contain residual amounts of D6 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.

The assessment considered potential exposure of Canadians to D6 from environmental sources (for example, air, water and soil), food and from using certain products available to consumers.
The assessment also indicated that D6 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.
D6 has been determined to be persistent (that is, remains for a long time) in air, water, and sediment.

Information available at the time of the assessment indicated that D6 may have effects to the liver and thyroid gland. These were considered the important or critical effects used for characterizing the risk to human health in the screening assessment.
The assessment also found that D6 had low potential to cause ecological effects.

Based upon a comparison of levels to which Canadians may be exposed to D6 and levels associated with health effects, the risk to human health for this substance was considered to be low.
Considering all the information presented in the ecological assessment, it was determined that the risk of harm to the environment from D6 is low.

The Government concluded that D6 is not harmful to human health at levels of exposure considered in the assessment, and that D6 is not entering the environment at levels that are harmful.

D6 may be found in certain products available to consumers. Canadians should follow any safety warnings and directions related to the product 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 D6. 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.