Silicones. Yes or no and why.
What are silicones?
Figure: the structure of silicones
Silicones are synthetic chemicals, long polymers made of many subunits of siloxane. Another name for them is polysiloxanes. They are colorless oils or rubber-like substances. Silicones are used in sealants, adhesives, lubricants, medicine, cooking utensils, thermal insulation, and electrical insulation.
They are also used as solvents in skincare products. Why?
From my book
You should use a cream that helps your skin keep water in and pollutants out. Silicones (the ingredient that gives a silky feel to creams and lotions) are perfect for this job, but will do nothing else for your skin and may even slow down the absorption of valuable nutrients.
I suggest you apply water-based serums first, on clean skin, before layering on creams containing silicones. This way, you’ll have a better chance of absorbing the nutrients before you apply the “seal” (silicones) to decrease trans-epidermal water loss.
You will find silicones in many “oil-free” products. They are not “edible” to skin (or acne) bacteria.
Environmental impact
Silicones are widely used in many industries, and the contribution of skincare to the whole is likely to be low. The environmental impact of any chemical depends on whether it is biodegradable (some plastics aren’t and that’s bad) and silicones are biodegradable (some faster and easier than others). So go ahead and take advantage of these synthetic compounds that make your skincare product better.
References
Lehmann RG, Miller JR, Kozerski GE. Degradation of silicone polymer in a field soil under natural conditions. Chemosphere. 2000 Sep;41(5):743-9. doi: 10.1016/s0045-6535(99)00430-0. PMID: 10834377.
Rościszewski, P., Łukasiak, J., Dorosz, A., Galiński, J., & Szponar, M. (1998). Biodegradation of polyorganosiloxanes. Macromolecular Symposia, 130(1), 337–346. doi:10.1002/masy.19981300129
Batich, C., DePalma, D., Marotta, J., Latorre, G. (1996). Silicone Degradation Reactions. In: Potter, M., Rose, N.R. (eds) Immunology of Silicones. Current Topics in Microbiology and Immunology, vol 210. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-85226-8_2