CYCLOMETHICONE

CYCLOMETHICONE

CYCLOMETHICONE

Cyclomethicone is a general term describing both individual and/or a mixture of cyclic siloxane materials that have many uses and are found in a variety of consumer products.
These materials are derived from the natural elements silicon and oxygen.

Cyclomethicones  are a group of methyl siloxanes, a class of liquid silicones (cyclic polydimethylsiloxane polymers)

The compound is classified as a cyclomethicone. Such fluids are commonly used in cosmetics, such as deodorants, sunblocks, hair sprays and skin care products.
It is becoming more common in hair conditioners, as it makes the hair easier to brush without breakage.
It is also used as part of silicone-based personal lubricants. D5 is considered an emollient.
In Canada, among the volume used in consumer products approximately 70% were for antiperspirants and 20% for hair care products.
10,000–100,000 tonnes per year of D5 is manufactured and/or imported in the European Economic Area.
Atmospheric emissions of D5 in the Northern Hemisphere were estimated to 30,000 tonnes per year.

Cyclopentasiloxane is widely used in cosmetics and body care products, such as skin care, sunscreen, makeup, hair conditioning products.

Cyclopentasiloxane can be directly used as the carrier or the main raw material, also can be used as an additive in aqueous systems through emulsification.

Cyclomethicone is a base fluid and volatile carrier suitable for use in a number of personal care products.
Cyclomethicone is non-greasy and leaves no oily residue or build-up and imparts a soft silky feel to skin.

Excellent spreading
Imparts soft silky feel to the skin
Leaves no oily residue or build up
Detackification
Non-greasy

Cosmetic Uses:
antistatic agents
hair conditioning
humectants
skin conditioning – emollient
solvents
viscosity controlling agents

Cyclomethicone is a generic group name for chemicals as:

Octamethylcyclotetrasiloxane (D4)
Cyclotrisiloxane (D3)
Cyclopentasiloxane (D5), Decamethylcyclopentasiloxane,  Cyclomethicone 5
Cyclopentasiloxane (D6)
Cycloheptasiloxane (D7)

Cyclomethicone” is actually used for a group of silicones with a ring structure. They are used to give a slippery feel, increase gloss and to make combing easier. They are “temporary” conditioners, meaning that while they are wet, they help with combing, and give a nice feel to skin or hair, but they do evaporate. They are clear, odorless, nonstaining, nongreasy, nonwaxy, nonsticky, and considered to be nonirritating to the skin and eyes. They are not soluble in water, but they do evaporate (without leaving a “cooling” feel as they do evaporate). Because they evaporate, they do not build up [Hunting (Conditioning) pg 170-171]. Some examples of Cyclomethicones are Cyclopentasiloxane (has 5 siloxane bonds in its ring), Cyclohexasiloxane (6 siloxane bonds), and Cycloheptasiloxane (7 siloxane bonds). The larger the ring (the more bonds), the slower they are to evaporate [Schueller pg 172-173]

Cyclomethicone is a synthetic silicone oil.
Cyclomethicone works in a variety ways, namely as a conditioning agent, solvent, humectant, carrying agent and viscosity controlling agent.
Like all other silicones, Cyclopentasiloxane has a unique fluidity that makes it easily spreadable.
When applied to the skin and hair, Cyclopentasiloxane gives a silky & slippery feeling to the touch and acts a mild water repellent by forming a protective barrier on the skin.

Cyclopentasiloxane can also fill in fine lines/wrinkles, giving the face a temporary “plump” look.

Functions:

Works in a variety ways, namely as a conditioning agent, solvent, humectant, carrying agent and viscosity controlling agent. Like all other silicones, this ingredient has a unique fluidity that makes it easily spreadable. When applied to the skin and hair, it gives a silky & slippery feeling to the touch and acts a mild water repellent by forming a protective barrier on the skin. It can also fill in fine lines/wrinkles, giving the face a temporary “plump” look.

Because its molecules are too big to physically penetrate the skin, it does not have any true moisturizing properties, but rather mostly functions as a carrying agent for other ingredients contained in a product. It’s particularly useful at quickly delivering nutrients to the skin & hair and evaporating into the air. It can also work as a base solvent for perfume oils and fragrance oils, as well as an anti-static agent. It’s particularly useful as a hair conditioner because it provides a silky feel with out weighing the hair down with greasy residue. It can be found in a variety of cosmetic products such as facial moisturizer/lotion, foundation, shampoo/conditioner, body spray, sunscreen, anti-aging treatment, antiperspirant/deodorant, concealer, hair dye and eye cream.

Cyclomethicone Emollient

A volatile silicone oil used in hair and skincare products to impart skin conditioning, emolliency, shine and/or silkiness; to reduce the greasy feel of tanning oils; promotes easy spreadability, and leaves a soft, silky smooth feel to the skin. Evaporates quickly leaving little residue on the skin.

Cyclomethicone is a blend of decamethylcyclopentasiloxane and dodecamethylcyclohexasiloxane with a low viscosity, a relatively high volatility and a cyclic structure.

It is non-polar and insoluble in water but completely miscible in lower alcohols, aliphatics, aromatics and halogenated solvents and can be used in antiperspirants and skin care formulations

Cyclomethicone is a colorless, odorless, transparent, nongreasy, silicone fluid.
It has a low viscosity and surface tension and a relatively high vapor pressure, which allows the majority of the silicone portion to evaporate from the surface to which it is applied.
Variations in the volatility of Cyclomethicone can be achieved through the blending of its different polymers.
Cyclomethicone is soluble in ethanol (99%), isopropanol (99%), mineral oil, paraffin wax, stearyl alcohol, stearic acid, and aliphatic, chlorinated, and fluorinated solvents.
It is highly insoluble in water but hydrolytically stable as to be easily emulsified into most cosmetic preparation^.’^)
Since the chemical name “Cyclomethicone” encompasses a number of different polymers, slight variations will exist in calculations of molecular weight, solubility, specific gravity, viscosity, and so on

Cyclomethicone is a cyclic polysiloxane compound used primarily as an emollient and solvent in cosmetic formulations

Why is it used in cosmetics and personal care products?
D5 and D6 are the predominant cyclomethicones used in cosmetics and personal care products, due to their excellent skin and hair conditioning properties.  Cyclomethicone D4 is rarely used as a cosmetic ingredient. D4 can also be present at very low residual levels (generally <0.1%) in D5 and D6, since it is used as a starting material in the production of those cyclomethicones. During this manufacturing process, virtually all of the material is consumed leaving only a tiny amount of D4.

Cyclomethicone ingredients are used in cosmetic products where eventual complete evaporation of the siloxane carrier fluid is desired. In this way they are useful for products like deodorants and antiperspirants that need to coat the skin but not remain tacky afterward. They provide other important product performance benefits such as facilitating a smooth texture and an even application.  Thus, they may also be found in sunscreens, shampoos, conditioners, moisturizers, lotions, etc.

The basic structure is common to all cyclomethicones: a cyclic backbone of siloxane units (i.e., silicon and oxygen with molecules of carbon and hydrogen attached, all very common elements found in nature).  Shorthand nomenclature is based upon the number of siloxane groups that are in the cyclic structure (see Figure 1).  Thus, cyclomethicone D5 (also known as cyclopentasiloxane) has five of these groups, cyclomethicone D4 (also known as cyclotetrasiloxane) has four, etc.

Cyclomethicone is a volatile, cyclic (circular) silicone fluid that has a lightning fast dry-time, making it the ideal carrier for fragrances because it instantly evaporates, leaving nothing behind but your chosen scent. Cyclomethicone (D5) will reduce the greasy feel of heavy emollients such as Shea Butter, makes an excellent emollient for “oil free” moisturizers, and offers light conditioning as well as improved dry and wet combout in hair care.

CYCLOMETHICONE
Cyclomethicone is a mixture of low molecular weight volatile cyclic siloxanes, in varying proportions. It provides excellent stability and is an ideal carrier for color cosmetics, make-up, skin creams and hair care products.

CYCLOMETHICONE is classified as :
Antistatic
Emollient
Hair conditioning
Humectant
Solvent
Viscosity controlling
CAS Number    69430-24-6 / 556-67-2 / 541-02-6 / 540-97-6
EINECS/ELINCS No:    – / 209-136-7 / 208-764-9 / 208-762-8
COSING REF No:    33101
INN Name:    cyclomethicone
Chem/IUPAC Name:    Cyclopentasiloxane, Decamethyl; Cyclic dimethylsiloxane pentamer; Cyclopolydimethylsiloxane; Decamethylcyclopentasiloxane

Cyclomethicones are nondegradable, inert polymers. In normal cosmetic conditions and formulations, they are nonreactive. Cyclomethicone is compatible with many organic and other silicones. The low volatility of Cyclomethicone allows the silicone portion to evaporate without cooling the skin like other volatile carrier fluids. By blending Cyclomethicones (mixtures of the n value in its structural formula), the volatility of the compound can be adjusted to correspond to the amount of time that the silicone portion is to contact the skin. At 22″C, the tetramer component (n = 4) evaporates nearly twice as slowly as water. The pentamer (n = 5) is much slower to evaporate than the tetramer.”‘

Cyclomethicone is used to blend with fragrance oils and perfume oils for after bath body mists. This product will produce a luxurious body spray that feels dry. Cyclomethicone is used in a wide variety of cosmetic applications such as antiperspirants, deodorants, lotions, creams, hair sprays, bath oils, makeup and nail polish. For making clear sprays, pour Cyclomethicone in bottle and add fragrance oil. Use in ratios of fragrance oil to Cyclomethicone from 1:3, to 1:6, or greater. Cyclomethicone blended with fragrance oils are bottled in PET containers with a fine mist sprayer. Do not use PVC as the fragrance oil will tend to breakdown and degrade the PVC.

Cosmetic Use
Cyclomethicone is used in cosmetic products primarily as a spreading or wetting agent. Because of its low viscosity, low surface tension, water repellency, and nongreasy texture, Cyclomethicone enhances spreading of highly viscous or waxy cosmetic systems. It is used todeposit or spread active ingredients, liquids, powders, or resins, and can provide light lubrication to hair and skin.(4’ Data obtained from the Food and Drug Administration (FDA) indicated that Cyclomethicone was used in a total of 168 product formulations. The FDA cosmetic product formulation computer printout”‘ is compiled through voluntary filing of such data in accordance with Title 21 part 720.4 of the Code of Federal Regulations.'”‘ Ingredients are listed in preset concentration ranges under specific product type categories. Since certain cosmetic ingredients are supplied by the manufacturer at less than 100% concentration, the value reported by the cosmetic formulator may not necessarily reflect the actual concentration found in the finished product. The actual concentration would be a fraction of that reported to the FDA. Data submitted within the framework of present concentration ranges provide the opportunity for overestimation of the actual concentration of an ingredient in a particular product. An entry at the lowest end of a concentration range is considered the same as one entered at the highest end of that range, thus introducing the possibility of a two- to ten-fold error in the assumed ingredient concentration. Table 2 includes the product formulation data for Cyclomethicone as reported by the FDA.”) Reported concentrations of Cyclomethicone in these products were present in all ranges of percentages. Products containing Cyclomethicone are applied to all areas of the skin, hair, nails, and mucous membranes. They may be applied several times a day and remain in contact with the skin for variable periods of time following each application. Daily or occasional use may extend over many years. Cyclomethicone is formulated in eye and face makeup, manicuring preparations, skin creams and oils, foot powders and sprays, and other personal care products. The low vapor pressure of the chemical also makes it useful in cologne and odor products.

Synonyms:
cyclopolydimethyl siloxane
cyclopolydimethylsiloxane
dimethyl cyclopolysiloxane
dimethylcyclopolysiloxane
dow corning 344
dow corning X 2-1401
gel base SIL
polydimethyl siloxy cyclics
polydimethylcyclosiloxane
sentry cyclomethicone

Noncosmetic Use Noncosmetic applications of Cyclomethicone include glass and specialty cleaners, lubricants, and penetrating oils.(*) Other chemicals not specifically referred to as nonvolatile silicones are reported as possible barriers in the prevention or recovery of skin damage.’4,9,’0) Some siloxane oils are widely used for their lubricating properties and water repellencyon walls, textiles, leather, in molds, and so on. Inhaled siliconeoil vapor has acted as an antifoaming agent in the treatment of chronic bronchitis.”) Polydimethylsiloxane, a specific silicone oil, also has been used in intraocular applications for the treatment of complicated retinal detachment.'”‘ International Use Cyclomethicone is an ingredient included in japan’s Comprehensive Licensing Standards of Cosmetics by Category
This publication includes those ingredients not in lapanese Standards of Cosmetic Ingredients (JSCI), lapanese Pharmacopoeia, or iapanese Standards of food Additives that may also be used in cosmetic products in japan. As stated in the Chemical and Physical Properties section, Cyclomethicone contains different polymers depending on the value of n in its chemical structure. In the Japanese monographs, Cyclomethicone is listed as Decamethyl Cyclopentasiloxane (n = 5) and Octamethyl Cyclotetrasiloxane (n = 4) in Part 1 (1986) and Part 2 (19871, respectively.

Cyclomethicone is a mixture of cyclic dimethylpolysiloxane compounds used primarily as an emollient and solvent in cosmetic formulations.
It is a colorless, odorless, silicone fluid that has a high vapor pressure and low surface tension and viscosity.
Cyclomethicone is soluble in aliphatic, chlorinated, and fluorinated solvents and is very insoluble in water.
Cyclomethicone is used in cosmetic formulations to deposit or spread active ingredients, liquids, powders, or resins, but also provides light lubrication and a silky feel to hair and skin. FDA data”‘ indicate that Cyclomethicone is used in 168 product formulations in all ranges of percentages.
. Noncosmetic use of Cyclomethicone includes its formulation in glass and specialty cleaners, lubricants, and penetrating oils.
There was no indication that Cyclomethicone was significantly absorbed through the skin.
Oral doses of a formulation containing Cyclomethicone were given to monkeys and humans.
A small amount of Cyclomethicone was absorbed and mostly recovered in the urine and expired air

Cyclomethicones are nondegradable, inert polymers.
In normal cosmetic conditions and formulations, they are nonreactive.
Cyclomethicone is compatible with many organic and other silicones.
The low volatility of Cyclomethicone allows the silicone portion to evaporate without cooling the skin like other volatile carrier fluids.
By blending Cyclomethicones (mixtures of the n value in its structural formula), the volatility of the compound can be adjusted to correspond to the amount of time that the silicone portion is to contact the skin. At 22″C, the tetramer component (n = 4) evaporates nearly twice as slowly as water.
The pentamer (n = 5) is much slower to evaporate than the tetramer.”‘

Cosmetic Use Cyclomethicone is used in cosmetic products primarily as a spreading or wetting agent.
Because of its low viscosity, low surface tension, water repellency, and nongreasy texture, Cyclomethicone enhances spreading of highly viscous or waxy cosmetic systems.
It is used todeposit or spread active ingredients, liquids, powders, or resins, and can provide light lubrication to hair and skin.

Products containing Cyclomethicone are applied to all areas of the skin, hair, nails, and mucous membranes.
They may be applied several times a day and remain in contact with the skin for variable periods of time following each application.
Daily or occasional use may extend over many years.
Cyclomethicone is formulated in eye and face makeup, manicuring preparations, skin creams and oils, foot powders and sprays, and other personal care products.
The low vapor pressure of the chemical also makes it useful in cologne and odor products.

Cyclomethicone is a clear, odorless silicone. It leaves a silky smooth feel when sprayed on the skin. Ideal for body sprays, lotions creams, bath salts, hair care, linen sprays etc
Cyclomethicone stays completely blended and crystal clear without shaking.

Uses:
Lotions: 1-20% to provide a soft velvety feel.
Bath Salts: Use instead of glycerin to add sheen to your bath salts and a silky feel to the bath water.
Hair Care: Spray on wet hair for easy combing or spray on hair to manage “frizz”.
After Bath Oil: Blend with your ultimate oil blend, add fragrance and you have a wonderful bath oil.
Room Sprays, Linen Sprays & Dry Perfume Oil: No more wet linens!

Noncosmetic Use Noncosmetic applications of Cyclomethicone include glass and specialty cleaners, lubricants, and penetrating oils.
(*) Other chemicals not specifically referred to as nonvolatile silicones are reported as possible barriers in the prevention or recovery of skin damage.
Some siloxane oils are widely used for their lubricating properties and water repellencyon walls, textiles, leather, in molds, and so on.

Polydimethylsiloxane, a specific silicone oil, also has been used in intraocular applications for the treatment of complicated retinal detachment.'”‘
International Use Cyclomethicone is an ingredient included in japan’s Comprehensive Licensing Standards of Cosmetics by Category
As stated in the Chemical and Physical Properties section, Cyclomethicone contains different polymers depending on the value of n in its chemical structure.
In the Japanese monographs, Cyclomethicone is listed as Decamethyl Cyclopentasiloxane (n = 5) and Octamethyl Cyclotetrasiloxane (n = 4) in Part 1 (1986) and Part 2 (19871, respectively.

Cyclomethicone is a mixture of cyclic dimethylpolysiloxane compounds used primarily as an emollient and solvent in cosmetic formulations.
It is a colorless, odorless, silicone fluid that has a high vapor pressure and low surface tension and viscosity.
Cyclomethicone is soluble in aliphatic, chlorinated, and fluorinated solvents and is very insoluble in water.
Cyclomethicone is used in cosmetic formulations to deposit or spread active ingredients, liquids, powders, or resins, but also provides light lubrication and a silky feel to hair and skin.
FDA data”‘ indicate that Cyclomethicone is used in 168 product formulations in all ranges of percentages.
Noncosmetic use of Cyclomethicone includes its formulation in glass and specialty cleaners, lubricants, and penetrating oils.
There was no indication that Cyclomethicone was significantly absorbed through the skin.
Oral doses of a formulation containing Cyclomethicone were given to monkeys and humans.
A small amount of Cyclomethicone was absorbed and mostly recovered in the urine and expired air
SPECIFICATIONS

Clear colourless liquid
characteristic odor
insoluble in water / alcohol
store tightly sealed, protected from heat and moisture
shelf life of 36 months when properly stored / handled
APPLICATIONS

Fragrances – Recommended use levels 0.5 – 3%.
Antiperspirants – Recommended use levels 3 – 10%.
Skin Care Products – Recommended use levels 3 – 10%.
Hair Conditioners – Recommended use levels 1 – 5%.
BENEFITS

No Oily Residue
Improves Efficacy of Antiperspirants
Dry, Non-Greasy Feel
Improves Wet Combing
Greater Flexibility in Formulating Cosmetic Products

Cyclomethicones are clear, odorless liquids utilized in skincare products to give your skincare that silky texture. Cyclomethicones are a type of silicone, so they help products to apply evenly and smoothly to your skin. There are several types of silicones used in skincare and cosmetic products. You may already be familiar with silicones, probably the one you are most acquainted with is dimethicone. Cyclomethicones have a similar function to dimethicone in that they help improve the texture of products, improve the appearance of scarring, improve the water-resistance of products, and emulsify the product. However, Cyclomethicones are also better at delivering active ingredients to the skin.

Cyclomethicones are a subclass of silicone; there are many different cyclomethicones in that subclass. Cyclomethicones are sometimes also called cyclosiloxanes, they are different names for the same class of chemicals. The two most commonly used cyclomethicones are cyclopentasiloxane and cyclohexasiloxane; you may have seen these ingredients somewhere near the bottom of your product’s ingredients list.

Cyclomethicones have a ring-shaped structure that makes it more volatile or less stable. This instability allows cyclomethicones to evaporate when applied to your skin—making cyclomethicones a great ingredient for products that need to go on smoothly but not remain sticky after application. As all the cyclomethicone eventually evaporates, it leaves behind the other key components in the product to work their magic. This action of evaporation makes it an excellent carrier ingredient.

Cyclomethicone
THE GOOD:Helps retain the skin’s moisture, improves the texture of products, and can help to deliver active ingredients to the skin.

THE NOT SO GOOD:It can cause some irritation to hypersensitive skin types.

WHO IS IT FOR?Most skin type except those with identified allergies to silicones

SYNERGETIC INGREDIENTS:Works well with most skincare ingredients but works exceptionally well at delivering key ingredients and fragrances.

KEEP AN EYE ON:There is no evidence to suggest that cyclomethicones cause clogged pores or breakouts. Congested skin types should be mindful that cyclomethicones can cause other products to be trapped close to the skin, potentially causing breakouts. This same process can also occur with sweat getting trapped under cyclomethicone, also causing breakouts.

What Are The Benefits of Cyclomethicone?
The main benefit of cyclomethicones is their ability to improve your product’s texture and sensory feel on the skin. However, cyclomethicones are also thought to help improve the appearance of dryness, are used for the appearance of scars, and may help to reduce irritation.

Texture
Cyclomethicones work to produce a smooth, silky feeling product. The structure of cyclomethicones, like most silicones, prevents the molecule from penetrating the skin. The structure allows for cyclomethicone containing products to glide over uneven texture and pores so that the product can be distributed evenly. They ensure that all areas of the skin are receiving the key ingredients in your product.

Dry skin
A study published in Skin Pharmacology and Physiology looked into the way cyclomethicones interacts with the skin. The study investigated the occlusive nature of the cyclomethicones. Occlusive substances work by creating a physical barrier between the skin and the air. The study’s results suggested that cyclomethicones are not an occlusive ingredient, and due to cyclomethicones being an unstable molecule, the evaporation means that they don’t form this barrier. These results are excellent news for congestive skin types, more on that later. However, occlusive barriers are generally useful for drier skin types, and it prevents moisture loss.  The rate at which the evaporation occurs provides the skin with a little bit of this protective barrier and may help to improve the appearance of dry skin and flakiness.

Scarring
Research into cyclomethicones has suggested their use in improving the appearance of scars in conjunction with other silicone ingredients. A study published in the Journal of Cutaneous and Aesthetic Surgery determined that silicone gel preparation significantly enhances the appearance of superficial, hypertrophic, and keloid scars.  While this research has not been conducted into cyclomethicones specifically, it is related to the broader subgroup of silicones.  Many of the silicone gel preparations contain cyclopentasiloxane or cyclohexasiloxane, which is used at the volatile element to deliver the other silicone ingredients to the skin.

Who Should Use Cyclomethicones?
Cyclomethicone products are suitable for most skin types, including congested, dry, or sensitive skin types, as well as skin types that may have damaged skin barrier integrity.

Acne and clogged pores
There is a general misconception that silicone-containing products cause breakouts. These claims remain unsubstantiated by peer-reviewed research. This misconception comes from anecdotal evidence, and while that can be a useful tool for driving areas of research, it does not replace an in-depth study. However, an explanation for this anecdotal evidence is that silicone-based products can trap sweat or other skincare products that potentially cause breakouts closer to the skin. This theory hasn’t been tested but has some validity given the function of silicones. To avoid this, make sure you wash your face after using silicone products and exercising. It would also be useful to check the ingredients in your other skincare products to see if they could be contributing to the breakouts.  Studies have determined that most silicone products are non-comedogenic (not clogging) and allow the skin to breathe. Silicones and cyclomethicones do not enter the pores, where the formation of blemishes occur. Silicones will also evaporate to varying degrees away from the skin, reducing the barrier effect. Cyclomethicones naturally form less of a barrier on the skin as they disappear more readily, minimizing the likelihood of congestion even further.

Sensitivity
Cyclomethicones can be beneficial for sensitive skin types as the barrier effect of products containing cyclomethicones can help to reduce the skin’s contact with irritants. If you have sensitive skin, be mindful of the other ingredients in your product that may irritate, such as fragrance, because the cyclomethicones will deliver these ingredients effectively to the skin. In some cases, minor irritation may occur from the use of silicones, but it’s not usually the source of sensitivity in a product.

Dry skin
Cyclomethicones may help to improve the appearance of dryness and flaking on the skin. As mentioned, silicones and cyclomethicones help to form a temporary breathable barrier on the surface of the skin, which may help to prevent moisture loss.4 Research is ongoing into the uses of silicones and cyclomethicone in issues that affect skin barriers such as psoriasis, eczema, and dermatitis.

Cyclomethicone vs Dimethicone
The main difference between cyclomethicones and dimethicone is that cyclomethicone has the ability to evaporate from the skin where dimethicone does not. This allows cyclomethicones to be a better carrier to deliver key ingredients to the skin. Dimethicone works best in products where the desired outcome is for the product to stay on the skin for prolonged periods of time. This makes dimethicone great for foundations, concealers and rich moisturizers.

Safety
Cyclomethicones have been well studied and are safe for their indicated uses.1 The main issue with cyclomethicones is that in some people, they can cause some minor irritation of the skin and eyes.  The report produced by the Cosmetic Ingredient Review group stated that cyclomethicones are safe for cosmetic use.

Other Uses
Some of the other uses for cyclomethicones include use in products that reduce the appearance of scars; it is present in gels designed for burns and may help in wound healing. Cyclomethicones are often used in hair care products to help improve the appearance of the hair, making it shiny and glossy. It is also undergoing research for use in head lice treatments.

JOURNAL OF THE AMERICAN COLLEGE OF TOXICOLOGY
Volume 10, Number 1,1991 Mary Ann Liebert, Inc., Publishers 2
Final Report on the Safety Assessment of Cyclomethicone
Cyclomethicone is a mixture of cyclic dimethylpolysiloxane compounds used primarily as an emollient and solvent in cosmetic formulations at concentrations from < 0.1 % to > 50%.
Cyclomethicone is not significantly absorbed through the skin. Small amounts of Cyclomethicone were absorbed by both humans and monkeys in oral feeding studies.
The absorbed Cyclomethicone was detected in both the urine and expired air.
Acute oral dose of Cyclomethicone to rats produced no deaths nor any gross lesions.
Short-term dermal studies produced no behavioral, local skin, gross, nor histopathological changes.
In subchronic inhalation studies in monkeys, no significant differences were found between exposed and unexposed animals.
Undiluted Cyclomethicone applied to the intact and abraded skin of rabbits produced little or no irritation in two studies.
Ocular studies indicated that Cyclomethicone produced only slight transient conjunctival irritation in washed and unwashed eyes.
Cyclomethicone did not produce reproductive effects in rats. Cyclomethicone was not a mutagen when assayed in the Ames test.
Cyclomethicone was neither irritating nor sensitizing to human skin in two clinical studies.
On the basis of the available data, it is concluded that Cyclomethicone is safe as a cosmetic ingredient in present practices of use.

Cyclomethicone, as manufactured by Dow Corning, includes four fluids, two of which have the tetramer (n = 4) as the primary component and two that contain primarily the pentamer (n = 5).
Since the particular properties for each of these four fluids are available (Table l), reference as to the polymer composition (e.g., n = 5, n = 4) of Cyclomethicone has been included where appropriate.
Because these fluids are so similar, references include not the specific fluid name but the general composition of the chemical.