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Silicones in cosmetics

This Q&A with NATRUE’s Dr Mark Smith reveals what you need to know about the silicones in personal care products
Katie Hill - Editor-in-Chief, My Green Pod
Cosmetics and silicones

We are all consciously trying to reduce our use of single-use plastic and the packaging we buy. Should we also be thinking about the ‘plastics’ – or manmade polymers – inside our products?

Consumers are concerned about the origin of the ingredients in their cosmetic products and the impact on the environment – from how they are sourced, to how the ingredients are made, what happens to those ingredients on their skin and what impact they then have on the environment after they are used.

When it comes to natural and organic cosmetics, for authenticity we should always think about what is inside the product to really understand a product’s claim to be ‘natural’ or ‘organic’.

For synthetic plastic materials like microbeads, we have witnessed a growing consumer and media interest, as well as different countries creating laws to ban these substances because of their environmental impact. In the UK the ban meant products had to be removed from stores by the end of 2018.

Nevertheless, for NATRUE it has always been the case that microbeads are banned from our certification standard, because of the strict requirements of the NATRUE Label. This means all products carrying our seal do not contain microplastics and never have.

What about the less obvious ‘plastic’ ingredients such as silicones? What do silicones do in our products, and why do manufacturers use them?

Plastics are polymers, but not all polymers are plastics, and silicones (not to be confused with the metallic substance silicon) are used abundantly in many different sectors, from materials that come into contact with food to paints and even electronics.

Silcones are relatively inexpensive ingredients that are commonly used because they are inert – meaning inactive chemically. In cosmetics, silicone-based ingredients perform a function in hair and skin conditioning; as emulsifiers, they help to combine other substances in the cosmetic; as an emollient they help to soften or smooth the skin surface and as a surfactant, they give better distribution or application of the product when used. They can also help control the thickness (viscosity) of a cosmetic product’s formulation, help hold or retain moisture (humectant) or reduce static, for instance in hair care products to avoid frizzing.

Are silicones liquids or solids? Are silicones available in different forms?

The term ‘plastic’ commonly means a polymer that can be moulded into a solid object like a microbead, for example. Synthetic polymers like silicones can also be moulded into solid objects like cookware. However, for cosmetic and personal care use, silicone-based ingredients are commonly liquid polymers.

What are silicones made from? What are the ingredient names to look out for on the INCI ingredients listing on the pack?

Silicones are synthetic polymers made up of silicon, oxygen and other elements, most typically carbon and hydrogen.

In cosmetics there are more than 300 possible ingredients that are made from or contain silicones. For instance, these polymers may be a purely synthetic form, or a combination of a synthetic polymer connected to a natural substance or substances.

Commonly you can identify a silicone-based cosmetic ingredient by the ending of the word on the ingredients (INCI) list on the back of the product packaging; look out for ‘-cone’ or ‘-siloxane’.

Some examples of ingredients are dimethicone, cyclomethicone, polysilicone, cyclopentasiloxane. Another is dimethicone – a silicone oil,often included as a conditioning agent.

Are silicones biodegradable or water soluble? How quickly do they break down, and do they contribute to the ‘plastic soup’ that is a problem for our waterways and oceans?

Some silicones are readily biodegradable, but others can persist in the environment, accumulate and be toxic. The factors influencing whether a silicone will biodegrade or not can also depend on where it ends up. For instance, on land one type of silicone may be broken down more easily but the same may not be true in our waterways or it may not be biodegradable at all. To this end, for cosmetic product use, silicones have recently raised concern due to their impact on the aquatic environment, especially since silicones can be found in rinse-off products.

Dr Mark Smith, NATRUE's director general

Two of the ingredients of notable concern are cyclopentasiloxane (D5) and cyclotetrasiloxane (D4). cyclotetrasiloxane (D4) was identified as negatively impacting the human reproduction system and accumulating in the environment with unpredictable long-term effects, and cyclopentasiloxane (D5) was also identified as being harmful to the environment.

Are silicones harmful to our health, skin or hair?

Due to their inert nature and ability to impart a number of beneficial functions to products, silicones have clear advantages for cosmetics and are deemed safe for use. Nevertheless, unlike some natural or naturally derived alternatives, there can be a concern that the short-term cosmetic or sensory fix does not benefit the use in the long term.

For example, silicones smooth the hair and make it feel glossy, but can accumulate in the hair over time, leaving it lank and heavy. As inert substances, they cannot nourish the skin like a plant oil that contains nutrients. This, combined with the noted impact of certain silicones on the environment and concerns for aquatic impact, has led consumers to seek out products without silicones.

What are the natural alternatives to silicones in certified natural and organic cosmetics?

For certified natural cosmetics bearing the NATRUE Label, the requirements of the label mean that silicones are not permitted. NATRUE requires that ingredients are readily biodegradable and made from natural, non-GMO, renewable sources, and manufactured using environmentally friendly processes.

Noted alternatives to silicones for use in a number of finished products can include substances like Dicaprylyl Ether, Undecane, Coco-Caprylate or Coco-Caprylate/Caprate. Each of these alternatives is built up from building blocks that come from vegetable origin, commonly available from coconut oil or certified palm oil.

Each of these examples is approved for use within the NATRUE criteria, where the plant origin must be non-GMO and the ingredient must be made originally from 100% natural substances – so there is no allowance for introducing portions of a molecule that is synthetic in origin – and the chemical modification of the plant substance uses only specific permitted chemical reactions. NATRUE classifies these ingredients as ‘derived natural’ substances.

Due to concerns over the environmental impact of silicones, we are seeing more and more natural alternatives appear on the market. This is a trend that will likely only increase.

Dr Mark Smith graduated with a MChem (Hons) degree in chemistry and an interdisciplinary PhD between chemistry and genetics. Before joining NATRUE in June 2014, he extended his research career with two positions covering biotechnology (Leeds, UK) and the biomedical/pharmaceutical sector (Montréal, Canada). In July 2016, Mark became Director of NATRUE where he takes the lead role in all political, regulatory and scientific affairs – advocacy, research and certification standard.

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