The Use of Silicones in Cosmetic Product Development

It is a fact that silicones are used in the majority of modern skin moisturisers that are on the market today. They are also used in a good many hair products so what are they, why do we use them and most importantly are they safe.

What Are They?

Silicones themselves do not occur naturally and the silicones supplied to the cosmetic industry are synthetically produced. However the process of production starts with a natural element: Sand (Silica SiO2). It is true to say therefore that silicones are derived from a natural occurring material just as it is true to say that most surfactants used in shampoos and body washes are derived from coconut or palm oil, or to put it in another context, that cheese is derived from milk.

So Silicones are chemicals but remember the air that we breath is made up of chemicals just as the water that we drink and need to survive is a chemical. Silicones contain a combination of Silicon and Oxygen atoms. Water is made up of Hydrogen and Oxygen atoms. In addition to Silica the silicones we use in cosmetics also contain varying combinations of hydrogen and carbon atoms. Carbon is the central element to all living organisms on earth. The human body is made up of approximately 18% carbon atoms. Carbohydrates, an important food group, contain only Carbon, Hydrogen and Oxygen.

Silicones are a class or group of chemicals (no ingredient has the name silicone).

Common INCI names for these are materials when they appear in cosmetics are:-

Dimethicone
Trisiloxane
Dimethiconol
Amodimethicone
Dimethicone crosspolymer
Trimethysiloxysilicate
Polymethylsilsesquioxane
Polypropylsilsesquioxane

Why Do We Use Them?

They are used extensively in cosmetics because very low levels can substantially improve the performance of a product. Here is a list of some of the properties and benefits.

From the chemists point of view they offer:-

Quick Spreading
Low Surface Friction
Low Surface Energy
Flexibility/ Elasticity
Permeability
Low Conductivity
UV Stable
Breathability

From the consumers point of view they provide:-

Smooth/ Soft Feel/ Sensory Enhancement
Ease of Use
Efficacy at Low Use Levels
Soft Focus
Heat Protection
Hair Repair
Hair Frizz Reduction
Improved Manageability
Add Texture to Formulation
Improved Resistance to Water and Sebum

Are they safe?

Biodegradability

Although silicones are not biodegradable, they are degradable either in the soil, for non volatiles polydimethylsiloxanes, or in the air for the volatiles types such as Cyclopentasiloxane.

It is important to understand the meaning of “biodegradable”.

The dictionary definition of Biodegradation is the chemical dissolution of materials by bacteria, fungi, or other biological means. Because silicones are inert under normal conditions they will not react with bacteria or fungi just as sand will not react with biological material and is not biodegradable.

It should be noted though that these materials do stay around for a long time and the use of some volatile silicones has been limited in cosmetics in the EU as they have been shown to accumulate in the environment.

Silicones in Skin Care

Typically silicones do not irritate skin/scalp. There is no evidence on negative impact to the scalp. Silicones are also typically used in antidandruff shampoos as part of scalp care where they help to counteract the negative impact of the anti-dandruff actives on conditioning.

Silicones are used in products positioned in the market for sensitive skin, where there are claims for treatments like rosacea, eczema, psoriasis, post-surgery, diaper rash and skin ulcers.

Most silicone molecules used in beauty care are either too large to enter the skin or they are volatile and therefore evaporate. They are often used in barrier creams designed to prevent skin sensitization to allergens.

When looking at other markets, such as healthcare, silicones can replace latex, a common allergen, in adhesives, gloves and a wide array of other items.

Silicone and organic/silicone combinations are also used to treat wounds, facilitate healing, reduce discomfort and do not promote bacterial growth.

Most silicones are invisible when they are resting on the skin, and some can absorb sebum and mattify the skin, minimizing visual appearance of pores in the process.

Any greasiness which is felt can often be attributed to the formulation design and not the silicone in itself.

Silicones are typically non-occlusive or “breathable” due to their chemical structure: They allow oxygen, nitrogen and water vapour to pass through them on the way to, or out of, the skin.

Silicones are non-comedogenic and non-acnegenic (will not give you blackheads or spots) and mostly non irritating. They also do not promote bacterial or other microbial growth.

However, they can aid the penetration of other ingredients for example actives.

Each formulation needs to be tested and evaluated for its specific properties, there are a wide range of ingredients and it will depend on their type, usage level and the skin type if the product can be considered non-comedogenic/acnegenic

Safety Overview in Beauty Care

Silicones used in personal care are stable and inert under conditions for the intended applications.

Silicones are among the most extensively studied materials used in consumer and industrial applications today.

More than 1,000 studies have been conducted by silicone manufacturers to assess the safety of silicones relative to workers, consumers, the environment and manufacturing processes. The results of this continued research and testing demonstrate the safety of silicones in their diverse and important applications.

These materials will continue to be used by the majority of mainstream cosmetic companies but there is a slow move towards silicone replacement materials with a more natural biodegradable starting point.

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