Dodecamethylcyclohexasiloxan

Suitable extinguishing media: Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.

Advice for firefighters: Wear self-contained breathing apparatus for firefighting if necessary.

Use water spray to cool unopened containers.

ACCIDENTAL RELEASE MEASURES: Personal precautions, protective equipment and emergency procedures: Avoid breathing vapors, mist or gas. Remove all sources of ignition. Beware of vapors accumulating to form explosive concentrations. Vapors can accumulate in low areas.; Environmental precautions: Prevent further leakage or spillage if safe to do so. Do not let product enter drains.; Methods and materials for containment and cleaning up: Contain spillage, and then collect with an electrically protected vacuum cleaner or by wet-brushing and place in container for disposal according to local regulations. Keep in suitable, closed containers for disposal.

SRP: Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in air, soil or water; effects on animal, aquatic and plant life; and conformance with environmental and public health regulations. If it is possible or reasonable use an alternative chemical product with less inherent propensity for occupational harm/injury/toxicity or environmental contamination.

Product: This combustible material may be burned in a chemical incinerator equipped with an afterburner and scrubber. Offer surplus and non-recyclable solutions to a licensed disposal company. Contaminated packaging: Dispose of as unused product.

Precautions for safe handling: Avoid inhalation of vapor or mist. Keep away from sources of ignition - No smoking. Take measures to prevent the build up of electrostatic charge.

Appropriate engineering controls: Handle in accordance with good industrial hygiene and safety practice. Wash hands before breaks and at the end of workday.

Gloves must be inspected prior to use. Use proper glove removal technique (without touching glove's outer surface) to avoid skin contact with this product. Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices. Wash and dry hands.

150 [mg/m3]

1700 [mg/m3]

9900 [mg/m3]

Eye/face protection: Safety glasses with side-shields conforming to EN166. Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU).

Handle with gloves.

Body Protection: Impervious clothing. The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace.

Respiratory protection: Where risk assessment shows air-purifying respirators are appropriate use a full-face respirator with multipurpose combination (US) or type ABEK (EN 14387) respirator cartridges as a backup to engineering controls. If the respirator is the sole means of protection, use a full-face supplied air respirator. Use respirators and components tested and approved under appropriate government standards such as NIOSH (US) or CEN (EU).

Surrounding breast tissues of women with silicone gel augmented breasts were sampled and analyzed by GC-MS. The tissues contained several cyclic siloxanes including dodecamethylcyclohexasiloxane at the following levels measured in ng/g; fat tissue (woman A = 780, woman B = 146); capsule tissue (woman B = 101.6, woman C = 251.1); muscle tissue (woman B = 25.08); fibrin layer (woman C = 385); breast tissue (none detected)(1). A study aimed at determining chemical composition and diffusion of low molecular weigh(LM) silicone gels from breast implants, detected dodecamethylcyclohexasiloxane by GC-MS and GC-AED. LM silicone breast implants dissolved in ethyl acetate showed approximately 1-2% of the total weight of the implant to be composed of linear and cyclic siloxanes including dodecamethylcyclohexasiloxane. Greatest diffusion rate of LM silicones into lipid-rich media was measured at 10 mg/day per 250 g implant at 37 °C(2).

In a national sampling survey in Sweden one or more cyclic siloxanes including dodecamethylcyclohexasiloxane (D6), decamethylcyclopentasiloxane (D5), and octamethylcyclotetrasiloxane (D4) were detected in 11 out of 49 human breast milk samples. The maximum concentration of dodecamethylcyclohexasiloxane was 4.8 ug/L. Linear siloxanes were detected in 6 of the samples at much lower levels(1).

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 870,000(SRC), determined from a structure estimation method(2), indicates that dodecamethylcyclohexasiloxane is expected to be immobile in soil(SRC). Volatilization of dodecamethylcyclohexasiloxane from moist soil surfaces is expected to be an important fate process(SRC) given a Henry's Law constant of 25.0 atm-cu m/mole(3). However, adsorption to soil is expected to attenuate volatilization(SRC). Dodecamethylcyclohexasiloxane is a volatile methylsiloxane that favors partitioning into the atmosphere(4); therefore, dodecamethylcyclohexasiloxane is expected to volatilize from dry soil surfaces(SRC) even with a vapor pressure of 0.0169 mm Hg(5). Evaporation of dodecamethylcyclohexasiloxane was measured in soil studies and found to occur with rates varying with moisture content, soil type and relative humidity(6). Volatilization from soil may be the major loss process under certain moist conditions(7). Dimethyl siloxanes, in general, are highly resistant to biodegradation(8). Biodegradation of dodecamethylcyclohexasiloxane of 4.47% using a 28 day ready-biodegradability test(7) suggests that biodegradation is not an important environmental fate process in soil(SRC). The abiotic degradation of volatile methylsiloxanes in soil (such as dodecamethylcyclohexasiloxane) is thought to occur via mechanisms such as hydrolysis reactions catalyzed by the surface activity of soil clays(6). Based on degradation studies in tropical (Hawaiian) and temperate soils(6), abiotic soil half-lives of 1.8-3.0 days and 158-202 days have been estimated for these two soil types, respectively(9).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 870,000(SRC), determined from a structure estimation method(2), indicates that dodecamethylcyclohexasiloxane is expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is expected(3) based upon a Henry's Law constant of 25.0 atm-cu m/mole(4). Using this Henry's Law constant and an estimation method(3), volatilization half-lives for a model river and model lake are 6.2 hours and 8.4 days, respectively(SRC). However, volatilization from water surfaces is expected to be attenuated by adsorption to suspended solids and sediment in the water column. The estimated volatilization half-life from a model pond is >1 year if adsorption is considered(5). According to a classification scheme(6), a BCF range of 1,160 to 1,660 measured in fathead minnows (Pimephales promelas)(7), suggests the potential for bioconcentration in aquatic organisms is very high(SRC). Dimethyl siloxanes, in general, are highly resistant to biodegradation(8). Biodegradation of 4.47% using a 28 day ready-biodegradability test(9) suggests that biodegradation is not an important environmental fate process in water(SRC). Based on measured aqueous hydrolysis rate data at higher temperatures, the hydrolysis half lives of dodecamethylcyclohexasiloxane at 25 °C were extrapolated to be 42 hours at pH4, 401 days at pH 7 and 125 hours at pH 9(9). However, strong adsorption to sediment may limit the rate of hydrolysis in natural waters(10).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), dodecamethylcyclohexasiloxane, which has a vapor pressure 0.0169 mm Hg at 25 °C(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase dodecamethylcyclohexasiloxane is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 9 days(SRC), calculated from its rate constant of 1.8X10-12 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). Methylcyclosiloxanes do not absorb UV light(4) and, therefore, dodecamethylcyclohexasiloxane is not expected to be susceptible to direct photolysis by sunlight(SRC). Volatile methylsiloxanes, which are primarily released or partitioned to the atmosphere(4), can be transported over long global distances, but they have a low potential for deposition to surface media in remote regions(5-7). Volatile methylsiloxanes have relatively short global residences times with the majority of global mass removed within 3 months of the end of release(4).

ENVIRONMENTAL: In a national sampling survey in Sweden one or more cyclic siloxanes including dodecamethylcyclohexasiloxane(D6), decamethylcyclopentasiloxane(D5), and octamethylcyclotetrasiloxane(D4) were detected in 11 out of 49 human breast milk samples. The maximum concentration of dodecamethylcyclohexasiloxane was 4.8 ug/L. Linear siloxanes were detected in 6 of the samples at much lower levels(1).

IDENTIFICATION AND USE: Typically including dodecamethylcyclohexasiloxane (D6) with a general formula of (-Si(CH3)2O-)x in a cyclic configuration, where x is generally less than 8, and more commonly x is 3-7. This formulation is commonly used in cosmetics. Other uses include electronics, furniture, health-care products, cookware, and medical devices. It is also used as surface treatments, paint, lacquers, and varnishes. HUMAN EXPOSURE AND TOXICITY: No data. ANIMAL STUDIES: D6 was not toxic in rats when given as a single dose orally, or dermally (2000 mg/kg). Eye instillation of the test substance induced conjunctival irritation (redness) in rabbits, and all reactions had cleared within 24 hours. The 4-hour dermal application of D6 did not induce irritation, corrosion, or staining in rabbits. In rats doses of 1000 or 1500 mg/kg body weight per day for 28 days did not produced signs of local or systemic toxicity. In reproductive/developmental toxicity screening tests in rats high dose animals demonstrated microscopic findings in liver (fatty change in females only), lung, and thyroid. An increase in the number of sperm-positive, non-gravid females was reported for the high dose group. In males, prothrombin time was prolonged at the 2 highest dose levels; however, there were no clinical indications of clotting abnormalities. Absolute and/or relative organ weight increases were observed in the liver and kidneys (both sexes) and in the adrenal glands (females only). Mutagenicity of D6 in the Salmonella typhimurium reverse mutation assay was evaluated using S. typhimurium strains: TA 98, TA100, TA1535, and TA1537. The mutagenicity of D6 was also evaluated in the Escherichia coli reverse mutation assay using E. coli strain WP2 uvrA. D6 was not mutagenic in the S. typhimurium reverse mutation assay or in the E. coli reverse mutation assay with or without activation.

Daily intake of dodecamethylcyclohexasiloxane from a variety of sources was estimated by Environment Canada as ranging from 28.7 ug/kg bodyweight for persons 60 years and older to 87.0 ug/kg bodyweight for children 6 months to 4 years of age. Environment Canada estimated the upper limit of daily systemic dose of dodecamethylcyclohexasiloxane from personal care products to be 100 ug/kg/body weight/day(1).

A study focused on determining environmental presence of cyclic dimethyl siloxanes in the Scandinavia region detected dodecamethylcyclohexasiloxane in marine mammals (seals/whales) at a concentration range of <5-7.9 ng/g wet weight. No cyclic dimethyl siloxanes were detected any of the seabird eggs tested(1). Analysis of seal blubber from grey seals (Halichoerus grypus) found in Sweden in 2008 detected dodecamethylcyclohexasiloxane levels of 4.4-9.5 ng/g wet weight(2).

A study focused on determining environmental presence of cyclic dimethyl siloxanes in the Scandinavia region detected dodecamethylcyclohexasiloxane in influent, effluent (treated/untreated) and industrial wastewater at a concentration range of <0.02 and 3.7 ug/L(1). It was detected in all 14 biologically digested sewage sludge samples with a total concentration of 26,000-30,000 ng/g dry weight. Dodecamethylcyclohexasiloxane was found at a concentration range of 220-11,000 ng/g dry weight(1). In Southwestern Ontario, Canada dodecamethylcyclohexasiloxane was detected in sewage treatment plant influents and effluents 0.49-27.33 ug/L and 0.97-2.71 ug/L, respectively(2). Dodecamethylcyclohexasiloxane was detected in all 8 wastewater treatment plant sludge samples collected from plants in northeastern China in 2009 at concentrations of 87.5-569 ng/g dry weight (mean of 179 ng/g)(3).

Using a structure estimation method based on molecular connectivity indices(1), the Koc of dodecamethylcyclohexasiloxane can be estimated to be 870,000(SRC). According to a classification scheme(2), this estimated Koc value suggests that dodecamethylcyclohexasiloxane is expected to be immobile in soil.

Shin-Etsu Silicones Amer Inc.; Acute toxicity study of KF-996s (dodecamethylcyclohexasiloxane) in Rats with cover letter dated 04/08/94. EPA Document No. 86940001751, Fiche No. OTS0572798.

Primary eye mucosa irritation study of KF-996S was conducted in nine Japanese white rabbits. In conclusion, extremely slight hyperemia (score: 0.5 points) in conjunctivae was observed in the instilled side in three animals at one hour after instillation. The total score of the findings was 0.2 points. Because the hyperemia in conjunctivae was not observed on or after 24 hours post instillation, it was thought that the finding was evanescent change. In addition, such slight hyperemia in conjunctivae could appear as a result of the instillation or examination processes. Therefore, the results do not always mean that KF-996S causes irritation. The other findings, namely chemosis and discharge in conjunctivae or changes in cornea and iris were not observed at any time of observation. Additionally, any differences in findings between the washed group and the unwashed group were not observed.

This study evaluated the absorption, distribution, and excretion of dimethyl cyclosiloxane fluids by the oral route in rats. Two Sprague Dawley rats were given a single oral gavage dose of the radiolabeled test substance at a dose of 600 mg/kg and placed in a Roth-type metabolism chamber. Expired air and excreta were collected for 72 hours. Urine and feces were collected at 24 hour intervals and radioactivity determined using liquid scintillation spectrometry. Expired air was passed over activated charcoal to trap metabolites and radioactivity was determined using liquid scintillation spectrometry. After obtaining the last urine sample, the animals were sacrificed and plasma and tissues were collected for total radioactivity analyses. No signs of systemic toxicity were noted. Approximately 53 and 86 percent of the total radioactivity was eliminated in the first 24 and 48 hours, respectively. Approximately 75 percent of the total radioactivity was eliminated in the feces, 13 percent in the expired air, and 2 percent in the urine. Trace amounts of radioactivity were seen in the liver, lungs, kidney, heart, and gastrointestinal tract. Based on the amount of total recovered radioactivity, approximately 15 percent of the administered dose was absorbed from the gas trointestinal tract.

Dow Corning Corp.; Determination of silicone absorbed by fish employed in a long term toxicity test (3 months) with cover letter dated 04/20/94. EPA Document No. 86940001581, Fiche No. OTS0572795.

For more TSCA Test Submissions (Complete) data for DODECAMETHYLCYCLOHEXASILOXANE (25 total), please visit the HSDB record page.

URBAN/SUBURBAN: Air monitoring conducted at urban sites in Downsview Ontario Canada, Paris France and Sydney Florida in 2009 detected dodecamethylcyclohexasiloxane levels of 4.0-53 ng/cu m(1). Outdoor air samples collected from various sites in Iowa contained dodecamethylcyclohexasiloxane concentrations <1.4-18 ng/cu m(2). Air monitoring conducted in Toronto Canada between March 2010 and April 2011 detected mean dodecamethylcyclohexasiloxane concentrations of 7.3-11 ng/cu m with a range of 1.9-22 ng/cu m(3).

INDOOR: A field study in Sweden collected indoor air samples in 400 homes as a part of the Dampness in Buildings and Health (DBH) study. The samples were taken in children's bedrooms. The results showed the presence of several siloxanes including dodecamethylcyclohexasiloxane in 142 of the 400 homes at a mean concentration of 7.9 ug/cu m and a range of 0.6 ug/cu m to 164 ug/cu m(1). Indoor air samples collected from various sites at the University of Iowa contained dodecamethylcyclohexasiloxane concentrations <59-2800 ng/cu m(2).

RURAL/REMOTE: A global monitoring study that collected air samples at remote arctic sites in Canada, the US (Alaska), and Norway in 2009 found dodecamethylcyclohexasiloxane concentrations of 0.13-1.5 ng/cu m(1); concentration at a remote Australia site was below detection limits (0.01 ng/cu m)(1). Air samples collected near a private home 70 km southwest Stockholm Sweden in Nov and Dec 2011 contained a mean dodecamethylcyclohexasiloxane concentration of 1.0 ng/cu m (range of 0.48-2.7 ng/cu m)(2). Air samples collected at the Zeppelin observatory in the remote Arctic in 2011 contained average decamethylcyclopentasiloxane concentrations of 0.23 and 0.45 ng/cu m in the late summer and early winter, respectively(3).

SOURCE DOMINATED: A study focused on determining environmental presence of cyclic dimethyl siloxanes in the Scandinavia region detected dodecamethylcyclohexasiloxane in air sampled near urban areas, landfills, sewage treatment plants, and other point sources. The concentration of dodecamethylcyclohexasiloxane ranged from 0.5-2.1 ug/cu m(1).

At the Norwegian Institute for Air Research in Kjeller Norge, a study sampling 10 fish species reported that cyclic siloxanes were not detected in fish muscle tissue by gas chromatography/high-resolution mass spectrometry (GC-HRMS)(1). A study focused on determining environmental presence of cyclic dimethyl siloxanes in the Scandinavia region detected dodecamethylcyclohexasiloxane in marine fish at a concentration range of <5-74 ug/g wet weight. No dodecamethylcyclohexasiloxane was detected in freshwater fish, however other cyclic dimethyl siloxanes were found(2). In Norway, the following concentrations of dodecamethylcyclohexasiloxane were measured (ng/g wet weight) for common mussels (1.3-1.8), flounder livers(1.4), flounder fillets (0.9), cod stomach contents (1.8-3.3), and cod livers (109.1-151.5)(3). Flounder (Pleuronectes flesus) collected from six sites in the lower Humber estuary in England in 2009 contained dodecamethylcyclohexasiloxane concentrations of 2.5-27 ng/g wet weight(4). Herring (Clupea harengus) collected off the Swedish coast in 2007 contained dodecamethylcyclohexasiloxane concentrations of 1-130 ng/g lipid weight(5). A 2012 study that collected fish from the Toyko Bay Japan (Japanese sea bass, red barracuda, chub mackerel, dotted gizzard shad, Japanese anchovy, sardine, white croaker) detected mean dodecamethylcyclohexasiloxane concentrations of 3.9-20 ng/g wet weight(6). Fish collected from the Oslofjord Norway during a 2010 study (Atlantic herring, coalfish, commond sole, Norway pout, European hake, starry skate, haddock, pollock, cod) contained mean dodecamethylcyclohexasiloxane concentrations of 2.3-26.8 ng/g wet weight and 96-803 ng/g lipid(6).

Dodecamethylcyclohexasiloxane's production and use as an intermediate in the manufacture of siloxane polymers, as an ingredient in cosmetics and personal care products, and as a defoamer in the processing of certain food products and in other industries(1) may result in its release to the environment through various waste streams(SRC). Similar to D5 (decamethylcyclopentasiloxane)(2), its use as volatile excipient in cosmetic products such as skin care products, deodorants/antiperspirants, hair care products and make-up products will result in its direct release to the environment through evaporation(2). Consumer and professional uses of personal care products containing dodecamethylcyclohexasiloxane result in 100% loss of the substance to the environment(3); the majority of this loss (90%) is to air and the remainder is lost to waste water(3).

Section 8(a) of TSCA requires manufacturers of this chemical substance to report preliminary assessment information concerned with production, exposure, and use to EPA as cited in the preamble in 51 FR 41329. Effective date: 10/12/93; Reporting date: 2/28/94.

Pursuant to section 8(d) of TSCA, EPA promulgated a model Health and Safety Data Reporting Rule. The section 8(d) model rule requires manufacturers, importers, and processors of listed chemical substances and mixtures to submit to EPA copies and lists of unpublished health and safety studies. Dodecamethylcyclohexasiloxane is included on this list. Effective date 10/12/93; Sunset date: 6/30/98.

Electronics, furniture, health-care products, cookware, and medical devices

Field of application: Surface treatments, paint, lacquers, and varnishes. /From table/

Cyclomethicone formulation containing dodecamethylcyclohexasiloxane (D6), decamethylcyclopentasiloxane (D5), and octamethylcyclotetrasiloxane (D4) are used in consumer products such as body lotion, hair styling products, lipstick, and deodorants.

Limited number of applications including some cosmetics, where it provides certain application-related benefits preferred by customers

The most important use, worldwide and in Canada, of D6 is as an ingredient in the formulation of personal care products and as an intermediate in the production of polydimethylsiloxanes (PDMS) silicone polymers ... D6 is also a constituent of cyclomethicone in the cosmetics industry ... In Canada, the most important uses of the mixtures of low molecular weight volatile cyclic siloxanes, which may contain a certain percentage of D6, are in the preparation of personal care products including hair and skin care products, and antiperspirants ... D6 was reported for use as a defoamer ... Defoamers are employed often at parts per million levels in a range of processing industries including pulp and paper, food, petrochemical, petroleum, and chemical manufacture as well as water treatment. Silicones are also used as defoamers in household products such as cleaners and detergents.

2023: 5,500,000 - <7,000,000 lb

Production volumes for non-confidential chemicals reported under the Inventory Update Rule.[Table#7388]

Cyclohexasiloxane, dodecamethyl- is listed as a High Production Volume (HPV) chemical (65FR81686). Chemicals listed as HPV were produced in or imported into the U.S. in >1 million pounds in 1990 and/or 1994. The HPV list is based on the 1990 Inventory Update Rule. (IUR) (40 CFR part 710 subpart B; 51FR21438).

Non-confidential 2012 Chemical Data Reporting (CDR) information on the production and use of chemicals manufactured or imported into the United States. Chemical: Cyclohexasiloxane, 2,2,4,4,6,6,8,8,10,10,12,12-dodecamethyl-. National Production Volume: 1,000,000 - 10,000,000 lb/yr.

Cosmetics product ingredient: Dodecamethylcyclohexasiloxane (D6) (Cyclohexasiloxane)

Information on 10 consumer products that contain Dodecamethylcyclohexasiloxane in the following categories is provided:

Plastics Product Manufacturing

Cyclohexasiloxane, 2,2,4,4,6,6,8,8,10,10,12,12-dodecamethyl-: ACTIVE

Cyclomethicone, is a common name for a mixture of cyclic dimethyl siloxanes

Cyclomethicone is a generic name for several cyclic dimethyl polysiloxane compounds ... it refers not only to octamethylcyclotetrasiloxane (D4), but also to cyclotrisiloxane (D3), cyclopentasiloxane (D5), cyclohexasiloxane (D6), and cycloheptasiloxane (D7), i.e. compounds of the general formula (CH3)2n-(O)n-(Si)n where n = 3-7.