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“If a personal care product is a gourmet meal, silicones should be the salt and spice and not the meat and potatoes.”
—Anthony J. O’Lenick Jr.
Bad news always makes headlines while good news is buried on Page 43, if mentioned at all. Lately, this is the case with silicones when some questions arose concerning their safety, particularly in regard to the environment. And the saber rattling in regulatory agencies, particularly those in Canada, seemed to threaten the industry. But when an extensively researched report clearly validating the safety of silicones in personal care was issued,1 consumer media was strangely silent.
Silicone-based molecules have unique properties and many uses in personal care; however, confusion over the chemistry has caused undue concern. While silicon (no “e” at the end) is an atom, larger polymeric structures formed from it are called silicones; and while an element such as carbon bonds to itself (–C-C-C-C-C-), silicon needs an oxygen in between (–Si-O-Si-O-Si-O-Si-). Concern centers on cyclic silicones, rings formed having four or five silicon atoms, also known as D4 or D5. The D comes from the standard shorthand for silicone units: M (mono), D (di), T (tri), Q (quat). It is easy to see how a row of D units swallowing its tail can form a ring, and how appending the number of D units results in D4, D5, D6—and the problems with cyclic silicones will be discussed later in this column.
Silicon accounts for 28% of the mass of the earth’s crust, so it is hardly an exotic material. The sand on a beach, concrete and computer chips are all created from silicones. Yet we now have to consider if chemically altered silicones are biodegradable or toxic to the environment. Also, as far as silicones being “natural,” even though the process starts with sand, so much energy and synthetic chemistry is employed to develop the silicones used in commerce that one is loathe to consider the process “green.”
Considering these questions as well as the aforementioned regulatory concerns rocking the foundations of the beauty industry, many companies have moved away from using some silicones as a precautionary response. Only one type of silicone—cyclic methylsiloxane—remains in the crosshairs, but it constituted 64% of the poundage of silicones used in 2009.2 To understand the problem, we must understand why one silicone is safe and appropriate for use in personal care and why there are issues with another kind of silicone.