Silicons in cosmetics, drugs and medical devices

Nowadays, we can often hear that certain cosmetic products do not contain parabens and silicones. About what parabens are, what they are used for and how dangerous they are, you can read here.

As for silicones, they are widely used in pharmaceutical, cosmetic and food industries, as well as in medical practice. Since 2002, approximately 470,000 tons of silicones have been produced in the United States and 800,000 tons in China. Impressive data suggest that silicones are popular raw materials, but the safety of their use is still controversial in scientific community.

1. What are silicones?

Silicones (polyorganosiloxans) are a group of synthetic organosilicon compounds based on monomer — [R2Si — O] —. Radical (R) in this structure can be methyl, ethyl, propyl phenyl and other groups. It is important to note that the safety of silicones will primarily be affected by two factors: chemical structure and particle size.  The smaller the particle size, the more dangerous the silicone. This is due to the fact that low-molecular siloxanes can easily penetrate through biological membranes and skin barriers, and also accumulate in the body.

You can learn silicones in the product by the characteristic endings -cone, -conol or siloxane:

1). Dimethicone copoliol, amodimethicone, trimethylsilylamodimethicone, dimethiconol

2). Octamethylcyclotetrasiloxane D4, decamethylcyclopentasiloxane D5, dodecamethylcyclohexasiloxane D6

As a rule, silicones perform in cosmetics the role of fillers, film forming agents, emollients in the composition of hair and skin care products.

2. Why are silicones dangerous?

It is worth noting that on the Russian market there are registered medicines based on dimeticone (Pepsan-R, Pancreoplat), intended for the treatment of digestive disorders, in in particular the elimination of increased gas formation in the intestine.

However, the notion of dimeticone may refer to about 62 different chemical compounds. Some of them include other substances that affect the chemical and rheological properties of the final product. According to the US safety assessment, all dimeticone compounds used in cosmetics are safe.

Drometrizole Trisiloxane is a popular UV filter that enters the market under the trade name Mexoryl XL of L'Oréal. Its content in finished products is regulated by TR CU 009/2011 and should not exceed 15%. Polysilicone15 also belongs to the category of UV filters, and its content is normalized and is 10%.  According to the European Chemicals Agency, inhalation of polysiloxane 15 vapors could lead to death. Other substances belonging to silicones are not regulated on the territory of the customs union.

If we talk about the use of silicones as fillers and breast implants, in 1964 the emergence of so-called “siliconomas” in response to injection of silicone-based preparations was described.  Siliconomas are a kind of granuloma, which is the immune response of the skin and is characterized by the formation of nodules. In this regard, in 1992 the FDA banned the use of these types of products in medical practice. Interestingly, in 2006 it was stated that there was no clear relationship between the emergence of autoimmune diseases and the use of silicone implants and the FDA lifted the moratorium on their use.

There are studies on the environmental problems of silicon accumulation in wastewater and river waters, as well as biogas, but clear conclusions on how these substances affect the environment  and human health is still not present.

Analysis of scientific sources and regulatory documents showed that silicones are generally a safe group of chemicals, if we talk about their use in cosmetics.  However, the data on silicones in medical devices (fillers and implants) is not unambiguous, and the use of silicones in this area is completely safe.

1. CU TR 009/2011 (ТР ТС 009/2011)
2. Mojsiewicz-Pieńkowska, K., Jamrógiewicz, M., Szymkowska, K., & Krenczkowska, D. (2016). Direct Human Contact with Siloxanes (Silicones) – Safety or Risk Part 1. Characteristics of Siloxanes (Silicones). Frontiers in Pharmacology, 7. doi:10.3389/fphar.2016.00132
3. Mojsiewicz-Pieńkowska, K., & Krenczkowska, D. (2018). Evolution of consciousness of exposure to siloxanes—review of publications. Chemosphere, 191, 204–217. doi:10.1016/j.chemosphere.2017.10.045
4. Becker, L. C., Bergfeld, W. F., Belsito, D. V., Hill, R. A., Klaassen, C. D., Liebler, D. C., … Andersen, F. A. (2014). Safety Assessment of Dimethicone Crosspolymers as Used in Cosmetics. International Journal of Toxicology, 33(2_suppl), 65S-115S. https://doi.org/10.1177/1091581814524963
5. Hughes, T. M., Martin, J. A., Lewis, V. J., & Stone, N. M. (2005). Allergic contact dermatitis to drometrizole trisiloxane in a sunscreen with concomitant sensitivities to other sun screens. Contact Dermatitis, 52(4), 226–227. doi:10.1111/j.0105-1873.2005.0566a.x
6. https://echa.europa.eu/substance-information/-/substanceinfo/100.102.446
7. Wang, L. L., Thomas, W. W., & Friedman, O. (2018). Granuloma Formation Secondary to Silicone Injection for Soft-Tissue Augmentation in Facial Cosmetics: Mechanisms and Literature Review. Ear, Nose & Throat Journal, 97(1-2), E46–E51. doi:10.1177/0145561318097001-211
8. Hajdu, Steven & Agmon-Levin, Nancy & Shoenfeld, Yehuda. (2010). Silicone and autoimmunity. European journal of clinical investigation. 41. 203-11. 10.1111/j.1365-2362.2010.02389.x.