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Last updated on June 25th, 2018
There is a lot of negative information about dimethicone on the Internet. In fact, this is one of the most controversial ingredients I have seen in my career as a consumer products researcher and educator. I have been researching dimethicone on and off for years now because I want to make sure that I use toxin-free makeup, skin care and personal care products and also that work well for women with wrinkles.
Sometimes what happens is that someone writes something bad about an ingredient, without providing a scientific or medical source of information. Others link to the original article, which creates a bad reputation on the internet. To make sure that I am passing along only the best information, I always read scientific studies on the subject to formulate my opinion.
Here is what I learned about this widely used ingredient.
Dimethicone’s chemical name is polydimethylsiloxane (PDMS), and it is also known simply as silicone oil.
The Skin Deep database powered by the Environmental Working Group (EWG) rates it 3 on a scale from 1 to 10 (10 being the most toxic) indicating that safety data is limited. While the Skin Deep database is the best tool we as consumers have for finding toxin-free makeup, skincare and personal care products, it has its limitations, so I often dig deeper.
Toxin-free makeup, skincare and personal care products would constitute products void of ingredients that can increase risks of allergic contact dermatitis, allergic reactions, skin irritation, cancer, and endocrine disruption.
The Cosmetic Ingredient Review (CIR) Panel reviewed the safety of dimethicone for use in cosmetics. It compiled all of the available data on dimethicone from over 100 independent studies. While I think the CIR panel is biased somewhat in favor of manufacturers and has lenient standards to arrive at their conclusions of safety, their assessments are helpful, if only to provide some context. I do not believe their conclusions are the last word on safety.
Dimethicone’s Effect on the Skin
In this case, dimethicone skin irritability tests referenced in the CIR report were done with the undiluted form of dimethicone, which would never happen with skin sensitizers such as formaldehyde-releasing preservatives. And even the undiluted form, it was not found to be an allergen in animal studies. It was also tested on 83 humans at 5% concentration and no skin reactions occurred.
In addition, I found it is NOT included in the Core Allergens of the American Society of Contact Dermatitis.
On the other hand, I found two studies (you can access them here and here) that show that dimethicone has been found to be effective to treat hand contact dermatitis and prevent contact dermatitis caused by SLS (Sodium Lauryl Sulfate).
Is dimethicone linked to cancer or endocrine disruption or any other health problems?
The CIR reports no links to cancer or endocrine disruption.
Furthermore, the CIR Expert Panel reports that the skin does not absorb dimethicone because of its large molecular weight.
There is some limited evidence regarding negative effects with inhalation exposure of aerosol formulation so I do not recommend dimethicone in products that you have to spray.
I also read a comprehensive write up on this widely used ingredient in the Ullmann’s Encyclopedia of Industrial Chemistry and the publication points out that it is a widely-researched substance because of its broad applications.
The 708-page manuscript states that it showed no health effects, even when it was administered orally in big doses.
Is dimethicone bad for the environment?
I was also concerned about dimethicone’s effects on the environment. Ullmann’s Encyclopedia of Industrial Chemistry explains that it is mostly non-biodegradable, but is not found to be harmful to aquatic life.
While it is non-biodegradable, it is eliminated from the sewage water because it is absorbed by sewage sludge. The reason it ends up in the oceans is that sewage sludge is often dumped into the oceans.
It is found that dimethicone dissolved in water has no harmful effects on aquatic organisms (plankton, crustacea, mussels, fish). Even silicone fluid administered with food showed no effect on fish. And the symbiosis of microorganisms such as bacteria and algae has not been disturbed by dimethicone dissolved in water.
Polydimethylsiloxanes in the form of an emulsion at concentrations up to 10,000 ppm exhibited toxic effects on fish but these are attributed to the emulsifiers.
And the good news is that polydimethylsiloxanes are found to be non-bioaccumulative, which means that as soon as a fish was transferred out of an environment where silicones were present, they were rapidly eliminated from its tissue.
In addition, polydimethylsiloxanes can be degraded and absorbed by the environment if a non-biological step is taken initially such as burning. You can read more about that here.
Thus, I am comfortable with the pure form of dimethicone used in beauty products when it is necessary for their performance.
Does it cause acne?
Since I had not found any concerning information on dimethicone, I was ready to try toxin-free makeup with it. The reason I wanted to try a foundation with it is that it helps the foundation spread evenly, conceal wrinkles, and in some cases can even create a dewy effect.
Some on the Internet claim that it creates an unbreathable layer on the skin, which may make the skin dry and even cause acne. I have been using Crunchi non-toxic liquid foundation that has this helpful ingredient in it for a few months now and have not had any acne problems.
If you have used products with dimethicone, please share your experience with us in the comments.
Conclusion about whether dimethicone belongs in toxin-free makeup
I have not found any evidence that this popular cosmetic ingredient is toxic when applied on the skin. Thus, I believe that it can be used in toxin-free makeup.
And lastly, I want to emphasize that this research pertains to a pure form of dimethicone, not the hybrid Dimethicone/Vinyl Dimethicone Crosspolymer used in the Beautycounter foundation or PEG-10 Dimethicone used in Bare Minerals foundation. I do not recommend these products.
To read about a non-toxic liquid foundation with a pure form of dimethicone, please click here.
Your Superpower To Read Ingredients
Imagine picking up any shampoo, conditioner, lotion, cream, or liquid foundation and in a matter of seconds being able to decide if you need to put it back on the shelf.
With this easy method, you will be able to spot potentially harmful personal care or skincare products that may cause irritation, an allergic reaction, or increase the risk of endocrine disruption or cancer.