Wednesday 18 March 2015

Glycerin - Bad for your skin?


Glycerin is a sugar alcohol that many of us have encountered in our everyday uses.2 For instance, it is found in moisturizers, pharmaceutical drugs, sweeteners and solvents.2 It is useful in moisturizers as it hydrates your skin layers, making your skin smoother.4 This is also beneficial for healing surgical wounds as glycerin will decrease the dryness, tightness, stinging and cracking of skin.4 In addition, glycerin also smoothness to liquor, soft drinks and toothpaste.3,5 When glycerin is orally ingested, it is sugary so it is often used to sweeten foods.
Since glycerin is found in food, it is not considered very toxic.5 During its production, glycerin is released into the environment but is degraded by living organisms and bacteria.5 Glycerin is also easily digested and metabolized by the human body to make glucose and glycogen which makes it a chemical of low concern.5 It also does not greatly irritate skin which is useful in moisturizers.5 
However, there is one concern about the way that glycerin moisturizes skin. Glycerin is hydrophilic so it will attract water to the top layer of skin.5 However, under low humidity conditions, it is believed that glycerin cannot grab enough water from the atmosphere.1 This forces glycerin to grab water from the lower layer which is even worse for your skin as this starts to dry out your lower skin layers.1 Luckily, glycerin is often combined with occlusive ingredients in moisturizers.1 Occlusive ingredients prevent water evaporation which prevents your skin from becoming dry.1 
Overall, glycerin is considered a useful, non-toxic, multi-purpose chemical. Some other options to glycerin in moisturizers are honeyquat, sodium lactate and sodium PCA.1 However, it has been shown that glycerin works more effectively than these alternatives so it is still the preferred choice.1

References
1) Barclay-Nichols, S. (2013). Question: Does glycerin draw water from your skin when the humidity is low? Retrieved March 2, 2015, from http://swiftcraftymonkey.blogspot.ca/2012/02/question-does-glycerin-draw-water-from.html
2) ChemIDplus: A Toxnet Database. (2015). Glycerin. Retrieved March 2, 2015, from http://chem2.sis.nlm.nih.gov/chemidplus/rn/56-81-5
3) Morrison, L. R. (2000). Glycerol. In 
Kirk-Othmer encyclopedia of chemical technology.
http://dx.doi.org/10.1002/0471238961.0712250313151818.a01
4) Silva, M. D. S., & Ferreira, P. C. (2012). Chemical Engineering Methods and Technology : Glycerol : Production, Structure, and Applications. Retrieved from http://library.mtroyal.ca:2052/lib/mtroyal/reader.action?docID=10681324
5) USDA AMS Agricultural Analytics Division for the USDA National Organic Program. (2013). Technical evaluation report. Retrieved from http://www.ams.usda.gov/AMSv1.0/getfile?dDocName=STELPRDC5104381

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