Silly Putty, Breast Implants, and Chicken Nuggets Are More Similar Than You Think

Silly Putty, Breast Implants, and Chicken McNuggets Think

Polydimethylsiloxane (PMDS) - a versatile chemical compound

What do Silly Putty, breast implants, and McNuggets have in common? The answer is... POLYDIMETHYLSILOXANE (PMDS). This versatile compound is made of a series of repeating units consisting of silicon bound to two oxygens and two CH3's known as methyl groups (1). Doesn't that sound delicious?

PMDS is an ingredient found in the oil used to make McDonald's Chicken McNuggets.

(2) Source: Evan-Amos. A pile of McDonalds Chicken McNuggets, as bought in America. https://en.wikipedia.org/wiki/Chicken_McNuggets#/media/File:McDonalds-Chicken-McNuggets.jpg (accessed November 22, 2015). Copyright 2011 by Evan-Amos. Reprinted with permission.

Aside from being found in McNuggets, polydimethylsiloxane is used for a variety of other purposes. In the medical world, you may find PMDS in not only breast implants, but also in soft contact lenses, and medical-grade wound dressing (3).

If you look at the back of your shampoo and conditioner, you may find that your hair is getting a dose of polydimethylsiloxane (4). But that isn't all, folks. PMDS is also an ingredient commonly found in industrial products such as caulking and in heat-resistant surface coatings (4). 

While we know where we can find polydimethylsiloxane, what is it about this compound that makes it so useful?

First off, PDMS is a BIG compound. It has a molecular weight of 6,800 to 30,000 Daltons (1). The cell membranes of body cells are only able to let small molecules pass through. As PDMS is a large molecule, it isn't able to pass through the cell membrane, accounting for its lack of toxicity (3). While its name may sound frightening, PMDS is not known to be a toxic compound. PMDS is not known to accumulate in human body tissues or cause any sort of negative cancer-causing or reproductive effects (3,5).

PDMS also has low water solubility (6). This property is particularly useful in PDMS's use in food. Polydimethylsiloxane is used in food products, or in the oil used to cook food products, to prevent foaming and caking, or the creation of clumps (5).

Regardless of how hard you look, you won't find PDMS in nature. PDMS is made using a series of industrial chemical steps (6).

Although PDMS isn't toxic and has a variety of uses, there is some controversy surrounding the compound. The notion of polydimethylsiloxane being a synthetic compound in food may frighten some people. However, at temperatures greater than 150 degrees Celsius, the compound is thought to break down into a toxic compound known as formaldehyde (4).

So what are some alternatives to PDMS, you may ask? Considering PDMS is used primarily as an anti-foaming agent, oil-based anti-foaming agents such as mineral and vegetable oil could be used (5). In addition, quillaia, which is the aqueous extract of the bark of the Quillaja saponaria Molina plant, is another anti-foaming agent alternative (5). 

With all of this in mind, you can feel a little bit more educated, and a little less guilty next time you order a ten pack of chicken McNuggets - or should I say, a ten pack of polydimethylsiloxane.

References

1. Polydimethylsiloxane. http://www.fao.org/ag/agn/jecfa-additives/specs/ Monograph1/Additive-315.pdf (accessed November 12, 2015).
2. Evan-Amos. A pile of McDonalds Chicken McNuggets, as bought in America. https://en.wikipedia.org/wiki/Chicken_McNuggets#/media/File:McDonalds-Chicken-McNuggets.jpg (accessed November 22, 2015). Copyright 2011 by Evan-Amos. Reprinted with permission.
3. Polydimethylsiloxanes. http://toxnet.nlm.nih.gov/cgi-bin/sis/search/a?dbs+hsdb:@term+@DOCNO+6775 (accessed November 16, 2015).
4. Roberts, Jeff. Domino’s, McDonald’s, & Wendy’s Are All Feeding You a Chemical Used In Silly Putty. http://www.collective-evolution.com/2014/01/26/dominos-mcdonalds-wendys-are-all-feeding-you-a-chemical-used-in-silly-putty/ (accessed November 16, 2015).
5. Msagati, T. A. M. The Chemistry of Food Additives and Preservatives [Online]; Wiley-Blackwell: Ames,Iowa, 2012; p 169-171.
6. Stevens, C., Powell, D.E., Makela, P., & Karman, C. Fate and effects of polydimethylsiloxane (PDMS) in marine environments. Marine Pollution Bulletin [Online]. 2001, 42, 536-543. https://www.dowcorning.com/content/publishedlit/26-1117-01.pdf (accessed November 12, 2015).