This post is sponsored by Grant Industries.

Silicones are one of the Big Bad ingredients in skincare, make-up and haircare. They’ve been demonised by natural brands, and there are more warnings about them than you can count. So I was delighted when Grant Industries (ingredient manufacturer, maker of Granactive Retinoid, physical sunscreens and of course, silicones) asked me to do a video to bust some myths about silicones.

For the video, scroll down to the bottom (or head to my YouTube channel) – otherwise, here’s the wordy version!

What is a silicone?

Silicones in beauty products are organosiloxanes. These contain alternating silicone-oxygen-silicone atoms, bonded to carbon. They’re made from sand (silicon dioxide).

There are a few different types of silicones in products, with varying properties and uses. In general, their names end in -cone, conol or -siloxane (ingredients that end in -silane usually don’t contain enough silicone to be classified as silicones and have different properties).

The major types of silicones are:

Small silicones: these tend to be very liquid, are often volatile (evaporate and don’t stay on hair or skin), e.g. phenyl trimethicone, cyclopentasiloxane
Silicone polymers: long chain molecules made up of repeating siloxane units, can be liquid or solid, e.g. dimethicone (polydimethylsiloxane or PDMS), polysilicone-11, polymethylsilsesquioxane
Functionalised silicones: contain other atoms on their structures which give them special properties on top of the usual silicone properties, e.g. amodimethicone, dimethiconol

Silicone Types

Why are silicones in beauty products?

Silicones have been used and researched since the 1950s, and are super common in beauty products, for good reason. They have some really cool properties that other ingredients just don’t have.

A lot of this comes from the fact silicones are very unreactive ingredients with a smooth glide. They’re also cruelty-free and vegan.

In skincare:

Silicones are hypoallergenic, non-irritating and non-comedogenic
They’re good moisturisers, and help products spread on your skin
They can enhance the penetration of active ingredients, and protect them from degrading before you apply them
Waterproofing silicones can be used in sunscreens to help them stay on
Silicones can be used to coat mineral sunscreen particles to stop clumping and to reduce free radical formation in sunlight
Silicones can also be used to protect your skin from wind and chafing.

In make-up:

Silicones glide onto your skin, so make-up blends easily
In make-up primers, they fill in lines and pores, making skin look plumper with less wrinkles, giving a smooth canvas for make-up
Silicones can give longwear properties to foundations and lipsticks, while keeping them flexible enough not to crack
Mattifying silicones can blur light, making skin look airbrushed

In hair care products:

Silicone Myths

So if silicones are so great, why are there so many myths about them?

Like with a lot of other beauty topics online, you’ll see myths that have no basis in reality, and you have myths that start with a grain of truth and quickly mutate into something else entirely.

Silicones are synthetic and not natural

This is true, and coupled with the fact they’re so popular, I think this is the main reason there are so many myths about silicones!

I’ve covered this topic before in an older video. Us humans have a bias towards thinking that natural means better, safer, more environmentally friendly, etc.

But that’s not true. Natural does not mean safer, and synthetic does not mean more dangerous for you or the environment! The most toxic substances in the world are natural. In beauty products, natural plant extracts are some of the ingredients that cause the most irritation and allergic reactions. When we use natural products, sometimes it’s incredibly destructive to the environment – things like palm oil, sandalwood, ivory, shark’s fin. You can check out my video on whether natural is better if you want more details.

So if the word “natural” doesn’t mean much – let’s ignore the “natural” part, and focus on the actual issues instead: the perception that natural things are safer for your body in terms of health, and better for the environment.

Silicones are bad for sensitive skin

This isn’t true – in fact it’s the opposite! Silicones are frequently used in medicine because they’re so hypoallergenic, non-irritating and unreactive.

Allergies to silicones are very rare even though they’re used so much, and dimethicone is even listed as FDA-approved skin protectant (and has been used effectively in products to decrease skin irritation). Most people can put undiluted dimethicone on their skin with no issues.

Silicones are toxic for your body

This is another one of those myths that grew from the whole “natural is better” notion. Silicones are actually very safe! They haven’t been linked to cancer or hormone disruption or any other long-term health effects, and regulatory authorities around the world (Health Canada, European Union’s Scientific Committee on Consumer Safety, UK Environment Agency, Cosmetic Ingredient Review (CIR), Australia’s Inventory Multi-tiered Assessment and Prioritisation (IMAP)) have said that they’re not a risk to humans.

(Note: I’ve linked assessments of small cyclic silicones like cyclopentasiloxane, since those are considered the most risky.)

Silicones are used in lots of medicated treatments like ointments and creams, and even inside the body in medical devices, pacemakers and hydrocephalic shunts in the brain. Silicones (specifically simethicone) are also in anti-farting oral medication, where it breaks up gas bubbles.

Silicones suffocate your skin and cause acne

A lot of the logic for why silicones are bad comes from the idea that they form a an occlusive, solid film on the skin. For example, you’ll often see that silicones are described as a “layer of rubber”, or that they trap dirt and germs in your pores like plastic wrap. Supposedly, this film interferes with your skin’s natural processes, so your skin can’t exfoliate, sweat, regulate its temperature properly, or even produce cells (though I’m not sure how that works, since cells are produced way lower than silicones can reach).

But this isn’t the case, and it’s hard to work out where it comes from other than just speculation – there’s zero research that shows any of this! (And in fact, there’s a study that found positive effects on skin physiology when a dimethicone-containing product was used.)

Silicones actually form a breathable layer on your skin – they’re permeable to oxygen and water vapour, and this is actually a problem when silicone rubber is used in equipment, since it can’t actually form a gas-tight seal. Oxygen and water molecules can wiggle out in between the flexible siloxane chains in a silicone layer.

Silicones also have low comedogenicity according to standard tests – dimethicone has a rating of 1, while cyclomethicone has a rating of 0. Any ingredient can cause acne, and silicones are the same as any other ingredient in that regard.

If you’ve used some products in the past and you’ve concluded that silicones are problematic for you – keep this in mind:

Lots of people will get breakouts from products and look for ingredients common in ingredients lists, and see dimethicone or other silicones and blame that. But silicones are incredibly common, some of the most common ingredients after water. And since so many products have silicones – somewhere around half of all skincare products – the chance of seeing them as ingredients in products that break you out is super high, even if they’re not actually the culprit.

There’s a perception that because silicones are used for longwear products, they’re hard to remove from your skin at the end of the day, and build up on your skin. But it’s really hard to make anything occlusive that stays on forever, because you shed one layer of skin cells a day. A buildup of silicone on your skin just doesn’t happen.

Silicones just makes your skin look nice but don’t actually do anything/makes your skin worse

In general, this is talking about dimethicone is in skincare, and it’s a similar accusation that gets thrown at petrolatum or petroleum jelly as well – that it forms an impenetrable occlusive film on your skin that dries out your skin and make it dehydrated.

But apart from the fact that water can actually pass through silicone films, some studies also show that silicones can improve your skin!

In one study, 2% silicone in cream led to greater skin hydration and lower TEWL than cream alone, so while it wasn’t entirely occlusive, it did help prevent water loss.
Another study found that TEWL was unaffected, which means that it wasn’t occlusive and it didn’t moisturise.
This study found positive effects on skin physiology when dimethicone was applied in combination with glycerin.

So silicone’s effect on the skin is dependent on the formulation, and the silicone used. Dimethicone also has protectant properties for your skin, and it’s included as a skin protectant on the FDA’s list of drug ingredients.

Actives can’t get through silicones

Silicones aren’t entirely occlusive, and the film they form breaks down over time. Silicones are actually used to deliver active ingredients in pharmaceuticals, and petroleum jelly, which is much more occlusive, is used for this as well. So yes, active ingredients can get through silicone films, and it won’t build up on your skin. Dimethicone also usually isn’t in products at a very high concentration, and even when it’s meant to form a barrier, sometimes… it just doesn’t work. Depending on your products though, within your skincare routine, it still might make sense to layer it over other ingredients if you want more immediate effects.

Silicones do nothing for your hair except coat it and make it look shiny

It’s true that silicones form a shiny coating on your hair… but this is a good thing!

Hair is pretty fragile, and if your hair is damaged it tends to snag, which leads to more damage. Smoothing out your hair is good – it stops cuticle scales from snapping off (which is what happens when you feel friction when you pull a comb through your hair), and it can make it stronger and more resistant to snapping. Silicones also protect your hair from heat when you dry or curl or straighten it. So they’re great at protecting your hair from damage, which is definitely doing something for your hair!

There’s one potential issue here though. Hairdressers tend to hate silicones because they stay on your hair and stops treatments from getting to your hair, so colouring and perming might not turn out as predicted. To avoid this issue, use a clarifying treatment before you go to the hairdresser, and stop using silicones a few days before you go to the salon.

Silicones stay on your hair and weigh it down

This can be the case for some people, for particular silicones. Different people have different hair needs, and not all silicones are the same. This “your mileage may vary” concept applies to other hair ingredients too, like oils and fatty alcohols.

For example, before I bleached and dyed my hair, I found that dimethicone was fantastic for my hair. Now it can sometimes feel a little heavy, but amodimethicone is amazing. It wasn’t heavy enough for my hair before bleaching, but now it’s perfect for targeting damage.

Silicones are non-biodegradable and toxic for the environment

Technically yes, silicones aren’t really biodegradable. But it’s important to note that this isn’t necessarily a bad thing!

“Biodegradable” means that something can be broken down by living things (e.g. bacteria). But non-biodegradable doesn’t mean that something is bad. For example, glass is non-biodegradable, but it’s inert and non-toxic, therefore it isn’t a big issue.

Silicones, on the other hand, aren’t biodegradable, but they are degradable – they degrade in the environment, and turn back into silica (sand), carbon dioxide and water.

For example, dimethicone is non-biodegradable, but it’s mostly removed in wastewater treatment, and degrades in contact with clays and sediment. It’s not very water soluble, so most of the time it ends up touching clay or so therefore probably ends up touching clay or sediment and degrading – just without any intervention by living organisms.

A lot of silicones also evaporate and degrade when they meet UV in sunlight and oxygen in the air. For most cyclic silicones used in beauty products, half will break down in 2 weeks. In soil and sediment, they break down in less than 2 years. This is relatively persistent from an environmental chemistry standpoint, but it’s really quick compared to the non-biodegradable things we usually think of, like plastics, which take thousands of years to break down. It’s also worth noting that the concentrations around the world are very low, even though we’ve been using them for a long time, which suggests that they’re not really building up in the environment.

The other issue is environmental toxicity. Most authorities around the world (Japan, Canada, Australia, US) think silicones are of little concern, given the low concentrations in the environment and their low solubility in water. The only region which has limits on silicones at the moment is the EU (ECHA), which limits D4 (cyclotetrasiloxane) and D5 (cyclopentasiloxane). The difference in the regulation between regions comes from Europe’s use of the precautionary principle, which means they focus on laboratory studies and the potential for harm over environmental evidence when making safety assessments.

At the moment with what we know, it doesn’t look like silicones are likely to be an environmental problem – although of course if new evidence comes up, it’ll need to be revisited.

VIDEO

Selected References

Englert C et al., Pharmapolymers in the 21st century: Synthetic polymers in drug delivery applications, Progress in Polymer Science 2018, 87, 107–164. DOI: 10.1016/j.progpolymsci.2018.07.005

Aliyar H & Schalau G II, Recent developments in silicones for topical and transdermal drug delivery (open access), Ther Deliv 2015, 6, 827-839. DOI: 10.4155/tde.15.39

SCCS (Scientific Committee on Consumer Safety), Opinion on cyclomethicone D4/D5, 22 June 2010

Mojsiewicz-Pieńkowska K et al., Direct human contact with siloxanes (silicones) – safety or risk part 1. Characteristics of siloxanes (silicones) (open access), Front Pharmacol 2016, 7, 132. DOI: 10.3389/fphar.2016.00132

Draelos ZD et al., The effect of vehicle formulation on acne medication tolerability, Cutis 2008, 82, 281-284.

De Paepe K, Silicones as nonocclusive topical agents, Skin Pharmacol Physiol 2014, 27, 164-171. DOI: 10.1159/000354914

Kwon SB et al., The effect of glycerin, hyaluronic acid and silicone oil on the hydration, moisturization and transepidermal water loss in human skin (open access), Kor J Aesthet Cosmetol 2013, 11, 761-768.

Hoggarth A et al., A controlled, three-part trial to investigate the barrier function and skin hydration properties of six skin protectants (open access), Ostomy Wound Manage 2005, 51, 30-42.

Zhai H et al., A bioengineering study on the efficacy of a skin protectant lotion in preventing SLS-induced dermatitis, Skin Res Technol. 2000, 6, 77-80.

Fowler JF Jr, Efficacy of a skin-protective foam in the treatment of chronic hand dermatitis, Am J Contact Dermat 2000, 11, 165-9. DOI: 10.1053/ajcd.2000.7184

Yahagi K, Silicones as conditioning agents in shampoos, J Soc Cosmet Chem 1992, 43, 275-284.

Rücker C & Kümmerer K, Environmental chemistry of organosiloxanes, Chem Rev 2015, 115, 466-524. DOI: 10.1021/cr500319v

Nendza M, Hazard assessment of silicone oils (polydimethylsiloxanes, PDMS) used in antifouling-/foul-release-products in the marine environment, Mar Pollut Bull 2007, 54, 1190-1196. DOI: 10.1016/j.marpolbul.2007.04.009

Bridges J & Solomon KR, Quantitative weight-of-evidence analysis of the persistence, bioaccumulation, toxicity, and potential for long-range transport of the cyclic volatile methyl siloxanes (open access), J Toxicol Environ Health B Crit Rev 2016, 19, 345-379. DOI: 10.1080/10937404.2016.1200505

Gobas FA et al., Fugacity and activity analysis of the bioaccumulation and environmental risks of decamethylcyclopentasiloxane (D5) (open access), Environ Toxicol Chem. 2015, 34, 2723-2731. DOI: 10.1002/etc.2942

Australia Department of Health, Cyclic volatile methyl siloxanes: Environment tier II assessment, 2 March 2018 (accessed 30 May 2019).

Lamb H, Scared sili: is tougher regulation required for silicone? E&T Magazine, 13 March 2019 (accessed 30 May 2019).

This video was sponsored by Grant Industries; however, the content is all my independent research and honest experience. For more information, see Disclosure Policy.

Silicone Mythbusting (with Video) syndicated from Lab Muffin Beauty Science
June 1, 2019 at 08:35AM

Dawn Siler

Saturday, June 1, 2019

Silicone Mythbusting (with Video)